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Charts 更改从时间序列图下载CSV中的日期格式_Charts_Time Series_Google Earth Engine - Fatal编程技术网

Charts 更改从时间序列图下载CSV中的日期格式

Charts 更改从时间序列图下载CSV中的日期格式,charts,time-series,google-earth-engine,Charts,Time Series,Google Earth Engine,我使用这个脚本生成NDVi与时间的关系图。问题是当我以CSV下载该系列时,日期格式很难使用,而且在所有观察中都不相同 原始CSV如下所示: system:time_start,NDVI Mar 26, 2013,0.132 我需要的是将日期格式更改为2013-03-26(yyyy-mm-dd) 剧本 var roi = /* color: #98ff00 */ee.Geometry.Point([-72.18245324628742, -13.260203147923505]); var l8

我使用这个脚本生成NDVi与时间的关系图。问题是当我以CSV下载该系列时,日期格式很难使用,而且在所有观察中都不相同

原始CSV如下所示:

system:time_start,NDVI
Mar 26, 2013,0.132
我需要的是将日期格式更改为2013-03-26(yyyy-mm-dd)

剧本

var roi = /* color: #98ff00 */ee.Geometry.Point([-72.18245324628742, -13.260203147923505]);
var l8toa = ee.ImageCollection("LANDSAT/LC08/C01/T1_RT");
// This field contains UNIX time in milliseconds.
var timeField = 'system:time_start';
// Use this function to mask clouds in Landsat 8 imagery. (See https://landsat.usgs.gov/collectionqualityband)
var maskClouds = function(image) {var quality = image.select('BQA');
var cloud01 = quality.eq(61440);
var cloud02 = quality.eq(53248);
var cloud03 = quality.eq(28672);
var mask = cloud01.or(cloud02).or(cloud03).not();
return image.updateMask(mask);};
// Use this function to add variables for NDVI, time and a constant
// to Landsat 8 imagery.
var addVariables = function(image) {
  // Compute time in fractional years since the epoch.
  var date = ee.Date(image.get(timeField));
  var years = date.difference(ee.Date('1970-01-01'), 'year');
  // Return the image with the added bands.
  return image
  // Add an NDVI band.
  .addBands(image.normalizedDifference(['B5', 'B4']).rename('NDVI')).float()
  // Add a time band.
  .addBands(ee.Image(years).rename('t').float())
  // Add a constant band.
  .addBands(ee.Image.constant(1));};
  // Remove clouds, add variables and filter to the area of interest.
  var filteredLandsat = l8toa  .filterBounds(roi)  .map(maskClouds)  .map(addVariables);
  // Plot a time series of NDVI at a single location.
  var l8Chart = ui.Chart.image.series(filteredLandsat.select('NDVI'), roi)
  .setChartType('ScatterChart')
  .setOptions({title: 'Landsat 8 NDVI time series at ROI',trendlines: {0: {color: 'CC0000'
  }},lineWidth: 1,pointSize: 3,
  });
print(l8Chart);

使用
DATE\u ACQUIRED
作为
xProperty
参数:

  var l8Chart = ui.Chart.image.series({ imageCollection:filteredLandsat.select('NDVI'), 
                       region:roi, xProperty:'DATE_ACQUIRED'})
  .setChartType('ScatterChart')
  .setOptions({title: 'Landsat 8 NDVI time series at ROI',trendlines: {0: {color: 'CC0000'
  }},lineWidth: 1,pointSize: 3,
  });