GEE——如何正确使用where函数将NDVI等指数进行分类

简介

我使用WHERE函数将NDVI指数分为5类，输出只给出一个数字，但不显示每一类的面积。

感谢您更正以下代码：

https://code.earthengine.google.com/f09e0bceeec40a5a8e370fe304fb7552

原始代码：

var geometry = 
    /* color: #d63000 */
    /* displayProperties: [
      {
        "type": "rectangle"
      },
      {
        "type": "rectangle"
      }
    ] */
    ee.Geometry.MultiPolygon(
        [[[[52.12940687787697, 29.917918770460375],
           [52.12940687787697, 29.917918770460375],
           [52.12940687787697, 29.917918770460375],
           [52.12940687787697, 29.917918770460375]]],
         [[[52.04151625287697, 29.900062859379428],
           [52.04151625287697, 29.830989901223244],
           [52.24339003217384, 29.830989901223244],
           [52.24339003217384, 29.900062859379428]]]], null, false);

Map.centerObject(geometry)
Map.addLayer(geometry)
// clip
function clip(image){
  return image.clip(geometry);
}

var modis_ndvi = ee.ImageCollection("MODIS/006/MOD13Q1")//MODIS/061/MOD13A2//MODIS/061/MOD13Q1
.filterDate('2020','2021')
.filterBounds(geometry)
.map(clip)

print(modis_ndvi,'modis_ndvi')

var ndvi_prepare = modis_ndvi.map(function(img){
return img.select('NDVI').multiply(0.0001)
.copyProperties(img, img.propertyNames())});

print(ndvi_prepare,'ndvi_prepare')


  var ndvi_area3 = ndvi_prepare.map(function(img){
var thr = img.where(img.lt(0.1),1);
  var thr2 = thr.where(img.gte(0.1).and(img.lt(0.2)),2);
  var thr3 = thr2.where(img.gte(0.2).and(img.lt(0.3)),3);
  var thr4 = thr3.where(img.gte(0.3).and(img.lt(0.4)),4);
  var thr5 = thr4.where(img.gte(0.4).and(img.lt(1.0)),5)
  var mask = thr5.updateMask(thr5)
  var area = mask.multiply(ee.Image.pixelArea