Javascript 为什么我在切换循环时得到NaN?
我正在尝试用javascript编写一个k-means函数。这是我的密码Javascript 为什么我在切换循环时得到NaN?,javascript,Javascript,我正在尝试用javascript编写一个k-means函数。这是我的密码 function kmeans(arrayToProcess,cluster_n){ var pointDimension = arrayToProcess[0].length; var ClusterResult = new Array(); var ClusterCenter = new Array(); var oldClusterCenter = new Array(); v
function kmeans(arrayToProcess,cluster_n){
var pointDimension = arrayToProcess[0].length;
var ClusterResult = new Array();
var ClusterCenter = new Array();
var oldClusterCenter = new Array();
var changed=false;
for(var i = 0;i<cluster_n;i++)
ClusterCenter.push(arrayToProcess[randomInt(arrayToProcess.length-1)]);
console.log(ClusterCenter);
// do{
for(var k=0;k<50;k++){//loop
for(var i = 0; i<cluster_n; i++){
ClusterResult[i] = new Array();
}
for(var i = 0; i<arrayToProcess.length; i++){
//for every point element
var oldDistance=-1;
var newClusterNumber = 0;
for(var j = 0; j<cluster_n; j++){
//for every cluster
var distance = Math.abs(computeDistanceBetween(arrayToProcess[i], ClusterCenter[j]));
if (oldDistance == -1){
oldDistance = distance;
newClusterNumber = j;
}else if ( distance <= oldDistance ){
newClusterNumber = j;
oldDistance = distance;
}
}
ClusterResult[newClusterNumber].push(arrayToProcess[i]);
}
oldClusterCenter = ClusterCenter;
//compute new centroid
for(var i = 0; i<cluster_n; i++){
newCentroid = pinit(pointDimension);
for(var j = 0; j<ClusterResult[i].length; j++){
newCentroid = padd(ClusterResult[i][j], newCentroid);
}
ClusterCenter[i] = pdivide(newCentroid, ClusterResult[i].length);
}
changed=false;
for(var i = 0; i<cluster_n; i++){
if(!pequal(ClusterCenter[i],oldClusterCenter[i]))
changed = true;
}
}//while (changed == true);
return ClusterResult;
}
function computeDistanceBetween(a,b){
var result = 0;
for(var i = 0; i<a.length;i++) result += a[i] * b[i];
return result;
}
function pinit(n){
var result = new Array(n);
for(var i=0;i<n;i++) result[i] = 0;
return result;
}
function padd(a,b){
var result = new Array(a.length);
for(var i = 0; i<a.length;i++) result[i] = a[i] + b[i];
return result;
}
function pdivide(a,d){
var result = new Array(a.length);
for(var i = 0; i<a.length;i++) result[i] = a[i] / d;
return result;
}
function pequal(a,b){
for(var i = 0; i<a.length;i++)
if(a[i] != b[i]) return false;
return true;
}
function randomInt(max){
return randomIntBetween(0,max);
}
function randomIntBetween(min,max){
return Math.floor(Math.random() * (max - min + 1)) + min;
}
函数kmeans(arrayToProcess,群集){
var pointDimension=arrayToProcess[0]。长度;
var ClusterResult=新数组();
var ClusterCenter=新数组();
var oldClusterCenter=新数组();
var=false;
对于(var i=0;i
上面的ClusterCenter将提供一些NaN项目。为什么
因为您正在以零对零跳转,这不是一个数字。这确实会发生在ClusterResult
中的每个空集群上-它将创建ClusterCenter[i]=pdivide(pinit(pointDimension),0);
如何处理空集群?我可能想到的策略是使0/0=0
,选择一个新的随机集群中心,或者将集群全部丢弃(cluster\n--
)
但是为什么一开始就有这么多空的集群呢?因为你的computeDistanceBetween
函数有严重缺陷。每一个(非0 | 0)点与自身相距较远。请选择更合理的距离函数,如欧几里德距离。它应始终返回正数,以呈现循环中的数学.abs
其他几点:
newCentroid
遗漏var
语句并泄漏到全局范围
- 您的
更改的存在缺陷。设置oldClusterCenter=ClusterCenter
时,两个变量将保留相同的数组,然后进行变异。不仅pequal(ClusterCenter[i],oldClusterCenter[i])
始终为真,甚至ClusterCenter[i]==oldClusterCenter[i]
因为oldClusterCenter===ClusterCenter
要解决此问题,请在分配后生成oldClusterCenter=ClusterCenter.slice()
或引入ClusterCenter=new Array(cluster\n);
- 计算最近集群的代码可以简化为
var newClusterNumber = 0,
oldDistance = computeDistanceBetween(arrayToProcess[i], ClusterCenter[0]));
for (var j=1; j<cluster_n; j++) {
var distance = computeDistanceBetween(arrayToProcess[i], ClusterCenter[j]);
if (distance <= oldDistance) {
newClusterNumber = j;
oldDistance = distance;
}
}
var newClusterNumber=0,
oldDistance=ComputedDistanceBetween(arrayToProcess[i],ClusterCenter[0]);
对于(var j=1;jfyn=不是一个数),当你在数学运算的中间放一些“不数字”时,JS返回这个例子。你能提供一些示例输入吗?还有,“如果我停止循环”和“如果我启动循环”意味着什么,代码的变化仅仅是不起作用的吗?@贝尔吉谢谢你的回答。我增加了“进一步的解释”。“示例输入”。@enapupe:实际上,这里的值确实来自对数字的数学运算:-)除以零返回“无穷大”@enapupe:请试试!什么是0/0
,Infinity/Infinity
?
var newClusterNumber = 0,
oldDistance = computeDistanceBetween(arrayToProcess[i], ClusterCenter[0]));
for (var j=1; j<cluster_n; j++) {
var distance = computeDistanceBetween(arrayToProcess[i], ClusterCenter[j]);
if (distance <= oldDistance) {
newClusterNumber = j;
oldDistance = distance;
}
}
var onewClusterNumber, ldDistance=Infinity;
for (var j=0; j<cluster_n; j++) {
var distance = computeDistanceBetween(arrayToProcess[i], ClusterCenter[j]);
if (distance <= oldDistance) {
newClusterNumber = j;
oldDistance = distance;
}
}