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Javascript 将变量文件名传递给topojson

javascript d3.js

Javascript 将变量文件名传递给topojson,javascript,d3.js,Javascript,D3.js,在以下功能中，我这样做是可行的： var land = topojson.feature(europe, europe.objects.nuts1); .border { stroke: #000; fill: none; } .graticule { fill: none; stroke: #777; stroke-width: .5px; stroke-opacity: .5; } div.tooltip { position: absolute;

在以下功能中，我这样做是可行的：

    var land = topojson.feature(europe, europe.objects.nuts1);

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
但如果我这样做，它会破坏：

var europe_path = "europe.objects.nuts1";

var land = topojson.feature(europe, europe_path);

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
出现此错误时
uncaughttypeerror:无法读取未定义的属性“length”

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
如何将变量传递给topojson

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
代码如下所示：

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->


.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->

.border{
行程：#000；
填充：无；
}
.分划{
填充：无；
行程：777；
笔划宽度：.5px；
笔画不透明度：.5；
}
分区工具提示{
位置：绝对位置；
文本对齐：居中；
宽度：84px；
高度：64px；
填充：2px；
字体：12px无衬线；
背景：浅灰色；
边界：0px；
边界半径：8px；
指针事件：无；
}
欧洲行政分区
资料来源1
资料来源2
​
var div=d3.选择（“主体”）.追加（“div”）
.attr（“类”、“工具提示”）
.样式（“不透明度”，0）；
可变宽度=600，
高度=500；
var projection=d3.geo.conicformaleurope（）；
var graticule=d3.geo.graticule（）；
var path=d3.geo.path（）
.投影（投影）；
//在此处查找新颜色：http://colorbrewer2.org/
var scale=d3.scale.quantize（）.domain（[10,60]）.range（colorbrewer.PuRd[3]）；
var svg=d3.选择（“正文”）.追加（“svg”）
.attr（“宽度”，宽度）
.attr（“高度”，高度）；
追加（“路径”）
.基准面（分划）
.attr（“类别”、“分划”）
.attr（“d”，路径）；
var dropdown=d3.选择（“#json_sources”）
var change=function（）{
var source=dropdown.node（）.options[dropdown.node（）.selectedIndex].value；
var str1=来源；
var str2=“.json”；
var file=str1.concat（str2）；
console.log（文件）；
var str_a=“europe.objects。”；
var str_b=来源；
var europe_path=str_a.concat（str_b）；
控制台日志（欧洲路径）；
json（文件，函数（错误，欧洲）{
d3.csv（“povertry_rate.csv”），函数（错误，povrate）{
var europe_path=“europe.objects.nuts1”；
var land=topojson.feature（欧洲，欧洲路径）；
数据={}；
povrate.forEach（功能（d）{
数据[d.GEO]=d['2013']；
});
控制台信息（数据）；
svg.selectAll（“路径”）
.数据（土地、地貌）
.输入（）
.append（“路径”）
.attr（“d”，路径）
.style（“笔划”，“#000”）
.style（“笔划宽度”，“0.5px”）
.样式（“填充”，功能（d）{
var值=数据[d.id]；
如果（isNaN（值））{
值=数据[d.id.子字符串（0,2）]；
}
如果（isNaN（值））{
返回“#fff”；
}
返回量表（值）；
})
.on（“鼠标悬停”，功能（d，i）{
var值=数据[d.id]；
如果（isNaN（值））{
值=数据[d.id.子字符串（0,2）]；
}
过渡部（）
.持续时间（200）
.样式（“不透明度”，0.9）；
div.html（“+d.properties.name+”
“+value+“%”）
.style（“左”，“d3.event.pageX）+“px”）
.style（“top”，（d3.event.pageY-28）+“px”）；
})
.on（“mouseout”，函数（d，i）{
过渡部（）
.持续时间（500）
.样式（“不透明度”，0）；
});
svg
.append（“路径”）
.style（“填充”、“无”）
.style（“笔划”，“#000”）
.attr（“d”，projection.getCompositionBorders（））；
});
})
}
下拉列表。打开（“更改”，更改）
改变（）//加载时触发json
您正在将europe\u路径定义为字符串“europe.object.nuts1”，而不是对象europe.object.nuts1。删除引用并尝试它

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
编辑开始****

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
如果目标是允许用户在两个层之间切换，则可以使用变量名动态加载topojson，如：

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->


.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
它采用的方法与所提供的代码类似

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
但是，如果目标是允许在两个或多个层之间切换，则可能更容易加载它们一次，并切换可见性，如中所示：

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->


.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
由于不需要从重新加载的topojson文件重新计算路径，因此这通常会更平滑、更快

.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->
编辑结束****

但是我需要把它作为一个字符串读入，你知道吗？有时它是坚果，有时它是坚果2，所以我想把它作为变量传递。我回答得太快了，没看透。在我点击entre后马上考虑一下，我只是把代码放进去——也许它会让你更好地了解我在做什么。基本上，我希望人们能够在两个地图视图之间切换：/what you mean？ 
.border {
  stroke: #000;
  fill: none;

}
.graticule {
  fill: none;
  stroke: #777;
  stroke-width: .5px;
  stroke-opacity: .5;
}

div.tooltip {
  position: absolute;
  text-align: center;
  width: 84px;
  height: 64px;
  padding: 2px;
  font: 12px sans-serif;
  background: lightgrey;
  border: 0px;
  border-radius: 8px;
  pointer-events: none;
}
</style>
<body>

<h1>Administrative Sub-Regions of Europe</h1>

<select id="json_sources" name="json_sources">
    <option value ="nuts1" selected>Source 1</option>
    <option value ="nuts2">Source 2</option>
<!--     <option value ="source3.json">Source 3</option> -->
</select>​


<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script src="http://d3js.org/colorbrewer.v1.min.js"></script>
<script src="https://cdn.rawgit.com/rveciana/d3-composite-projections/v0.2.0/composite-projections.min.js"></script>
<script>

var div = d3.select("body").append("div")
        .attr("class", "tooltip")
        .style("opacity", 0);

var width = 600,
    height = 500;

var projection = d3.geo.conicConformalEurope();
var graticule = d3.geo.graticule();

var path = d3.geo.path()
    .projection(projection);


// Find new colours here: http://colorbrewer2.org/
var scale =  d3.scale.quantize().domain([10,60]).range(colorbrewer.PuRd[3]);
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);


    svg.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", path);



var dropdown = d3.select("#json_sources")
var change = function() {
  var source = dropdown.node().options[dropdown.node().selectedIndex].value;


var str1 = source;
var str2 = ".json";
var file = str1.concat(str2);
console.log(file);

var str_a = "europe.objects.";
var str_b = source;
var europe_path = str_a.concat(str_b);
console.log(europe_path);


  d3.json(file, function(error, europe) {

  d3.csv("povertry_rate.csv", function(error, povrate) {

    var europe_path = "europe.objects.nuts1";

    var land = topojson.feature(europe, europe_path);

    data = {};
    povrate.forEach(function(d) {
      data[d.GEO] = d['2013'];
    });


    console.info(data);
    svg.selectAll("path")
      .data(land.features)
      .enter()
      .append("path")
      .attr("d", path)
      .style("stroke","#000")
      .style("stroke-width",".5px")
      .style("fill",function(d){
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            if (isNaN(value)){
              return "#fff";
            }

            return scale(value);
            })
      .on("mouseover", function(d,i) {
            var value = data[d.id];
            if (isNaN(value)){
              value = data[d.id.substring(0,2)];
            }
            div.transition()
                .duration(200)
                .style("opacity", 0.9);
            div.html("<b>"+d.properties.name+"</b><br/>" + value + "%")
                .style("left", (d3.event.pageX) + "px")
                .style("top", (d3.event.pageY - 28) + "px");
        })
      .on("mouseout", function(d,i) {
          div.transition()
              .duration(500)
              .style("opacity", 0);
        });

        svg
          .append("path")
            .style("fill","none")
            .style("stroke","#000")
            .attr("d", projection.getCompositionBorders());


  });




  })
}

dropdown.on("change", change)
change(); //trigger json on load



</script>






</body>

<!-- // d3.json("nuts2.json", function(error, europe) {

// }); -->