此演示使用手动定位点来训练分类器。每个训练点都有一个名为“landcover”的字段，其中包含该位置的类标签。以下块包含点的构造代码。将鼠标悬停在“城市”变量上并单击对话框中的“转换”。

分类中使用了三个一个是城市一个是农田一个是水域，因为分类比较简单，所采集的样本数量也比较少。

 最后分类的结果

 文中涉及一些方法，不懂的可以自己去文档中参考

代码：

// This demonstration uses hand-located points to train a classifier.
// Each training point has a field called 'landcover' containing
// class labels at that location. The following block contains
// construction code for the points.  Hover on the 'urban' variable
// and click, 'Convert' in the dialog.
var urban = /* color: #ff0000 */ee.FeatureCollection(
        [ee.Feature(
            ee.Geometry.Point([-122.40898132324219, 37.78247386188714]),
            {
              "landcover": 0,
              "system:index": "0"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.40623474121094, 37.77107659627034]),
            {
              "landcover": 0,
              "system:index": "1"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.39799499511719, 37.785187237567705]),
            {
              "landcover": 0,
              "system:index": "2"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.39936828613281, 37.772162125840445]),
            {
              "landcover": 0,
              "system:index": "3"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.41104125976562, 37.76890548932033]),
            {
              "landcover": 0,
              "system:index": "4"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.41859436035156, 37.7835592241132]),
            {
              "landcover": 0,
              "system:index": "5"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.41790771484375, 37.801465399617314]),
            {
              "landcover": 0,
              "system:index": "6"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.40142822265625, 37.77053382550901]),
            {
              "landcover": 0,
              "system:index": "7"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.39662170410156, 37.75370595587201]),
            {
              "landcover": 0,
              "system:index": "8"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.28950500488281, 37.8166551148543]),
            {
              "landcover": 0,
              "system:index": "9"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.28195190429688, 37.82696064199382]),
            {
              "landcover": 0,
              "system:index": "10"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.28126525878906, 37.81882481909333]),
            {
              "landcover": 0,
              "system:index": "11"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.2723388671875, 37.82858769894982]),
            {
              "landcover": 0,
              "system:index": "12"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.28607177734375, 37.84702517033112]),
            {
              "landcover": 0,
              "system:index": "13"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.29293823242188, 37.8562421777618]),
            {
              "landcover": 0,
              "system:index": "14"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.27302551269531, 37.849193981623955]),
            {
              "landcover": 0,
              "system:index": "15"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.28057861328125, 37.86545803289311]),
            {
              "landcover": 0,
              "system:index": "16"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.27096557617188, 37.820452055421086]),
            {
              "landcover": 0,
              "system:index": "17"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.27920532226562, 37.808518155993234]),
            {
              "landcover": 0,
              "system:index": "18"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.27783203125, 37.80092285199884]),
            {
              "landcover": 0,
              "system:index": "19"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.31491088867188, 37.784644570400836]),
            {
              "landcover": 0,
              "system:index": "20"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.31903076171875, 37.7835592241132]),
            {
              "landcover": 0,
              "system:index": "21"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.26959228515625, 37.80200794325057]),
            {
              "landcover": 0,
              "system:index": "22"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.40966796875, 37.768362702622596]),
            {
              "landcover": 0,
              "system:index": "23"
            })]),
    vegetation = /* color: #3b8b00 */ee.FeatureCollection(
        [ee.Feature(
            ee.Geometry.Point([-122.15835571289062, 37.81990964729775]),
            {
              "landcover": 1,
              "system:index": "0"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.14462280273438, 37.806890656610484]),
            {
              "landcover": 1,
              "system:index": "1"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.16522216796875, 37.817197546892785]),
            {
              "landcover": 1,
              "system:index": "2"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.09793090820312, 37.80797566018445]),
            {
              "landcover": 1,
              "system:index": "3"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.08282470703125, 37.81123057525427]),
            {
              "landcover": 1,
              "system:index": "4"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.07733154296875, 37.7992951852321]),
            {
              "landcover": 1,
              "system:index": "5"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.05398559570312, 37.77867496858311]),
            {
              "landcover": 1,
              "system:index": "6"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.05398559570312, 37.76673431862507]),
            {
              "landcover": 1,
              "system:index": "7"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.07389831542969, 37.792784159505125]),
            {
              "landcover": 1,
              "system:index": "8"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.0306396484375, 37.83455326751277]),
            {
              "landcover": 1,
              "system:index": "9"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.06497192382812, 37.831299380818606]),
            {
              "landcover": 1,
              "system:index": "10"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.19268798828125, 37.85461573076714]),
            {
              "landcover": 1,
              "system:index": "11"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.18170166015625, 37.849193981623955]),
            {
              "landcover": 1,
              "system:index": "12"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.51609802246094, 37.84051835371829]),
            {
              "landcover": 1,
              "system:index": "13"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.49137878417969, 37.838349287273296]),
            {
              "landcover": 1,
              "system:index": "14"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.50511169433594, 37.82641828170282]),
            {
              "landcover": 1,
              "system:index": "15"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.54081726074219, 37.84160286302103]),
            {
              "landcover": 1,
              "system:index": "16"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.55592346191406, 37.85353141283498]),
            {
              "landcover": 1,
              "system:index": "17"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.56278991699219, 37.86274760688767]),
            {
              "landcover": 1,
              "system:index": "18"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.54631042480469, 37.86328970006369]),
            {
              "landcover": 1,
              "system:index": "19"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.52708435058594, 37.85190490603355]),
            {
              "landcover": 1,
              "system:index": "20"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.52845764160156, 37.83889155986444]),
            {
              "landcover": 1,
              "system:index": "21"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.51472473144531, 37.83021472002989]),
            {
              "landcover": 1,
              "system:index": "22"
            })]),
    water = /* color: #0300ff */ee.FeatureCollection(
        [ee.Feature(
            ee.Geometry.Point([-122.61085510253906, 37.835095568009415]),
            {
              "landcover": 2,
              "system:index": "0"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.60673522949219, 37.8166551148543]),
            {
              "landcover": 2,
              "system:index": "1"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.60810852050781, 37.80038030039511]),
            {
              "landcover": 2,
              "system:index": "2"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.57102966308594, 37.80472060163741]),
            {
              "landcover": 2,
              "system:index": "3"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.58888244628906, 37.83455326751277]),
            {
              "landcover": 2,
              "system:index": "4"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.65205383300781, 37.855157883752504]),
            {
              "landcover": 2,
              "system:index": "5"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.62870788574219, 37.823164036248635]),
            {
              "landcover": 2,
              "system:index": "6"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.62664794921875, 37.792784159505125]),
            {
              "landcover": 2,
              "system:index": "7"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.60055541992188, 37.792784159505125]),
            {
              "landcover": 2,
              "system:index": "8"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.53738403320312, 37.7992951852321]),
            {
              "landcover": 2,
              "system:index": "9"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.57240295410156, 37.82641828170282]),
            {
              "landcover": 2,
              "system:index": "10"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.58682250976562, 37.823164036248635]),
            {
              "landcover": 2,
              "system:index": "11"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.36709594726562, 37.85570003275074]),
            {
              "landcover": 2,
              "system:index": "12"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.40074157714844, 37.88171849539308]),
            {
              "landcover": 2,
              "system:index": "13"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.40005493164062, 37.86925246182428]),
            {
              "landcover": 2,
              "system:index": "14"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.37739562988281, 37.88117653780091]),
            {
              "landcover": 2,
              "system:index": "15"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.34992980957031, 37.87358871277159]),
            {
              "landcover": 2,
              "system:index": "16"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.34992980957031, 37.85244707895444]),
            {
              "landcover": 2,
              "system:index": "17"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.34855651855469, 37.838349287273296]),
            {
              "landcover": 2,
              "system:index": "18"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.39387512207031, 37.849193981623955]),
            {
              "landcover": 2,
              "system:index": "19"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.44743347167969, 37.82262164805511]),
            {
              "landcover": 2,
              "system:index": "20"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.43850708007812, 37.842687356377084]),
            {
              "landcover": 2,
              "system:index": "21"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.354736328125, 37.789528431453014]),
            {
              "landcover": 2,
              "system:index": "22"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.25826263427734, 37.68952589794135]),
            {
              "landcover": 2,
              "system:index": "23"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.53326416015625, 37.81114015184751]),
            {
              "landcover": 2,
              "system:index": "24"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.44503021240234, 37.87078823552829]),
            {
              "landcover": 2,
              "system:index": "25"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.4532699584961, 37.86048883137166]),
            {
              "landcover": 2,
              "system:index": "26"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.33036041259766, 37.833920567528345]),
            {
              "landcover": 2,
              "system:index": "27"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.19989776611328, 37.65664491891396]),
            {
              "landcover": 2,
              "system:index": "28"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.21946716308594, 37.62374937200642]),
            {
              "landcover": 2,
              "system:index": "29"
            }),
        ee.Feature(
            ee.Geometry.Point([-122.24040985107422, 37.61504728801728]),
            {
              "landcover": 2,
              "system:index": "30"
            })]);

// 加载 Landsat 8 缩放辐射图像集合。
var landsatCollection = ee.ImageCollection('LANDSAT/LC08/C01/T1')
    .filterDate('2017-01-01', '2017-12-31');

// 简单除云
//asFloat:如果为真，则输出波段与 Landsat.TOA 算法的单位相同；如果为 false，TOA 值将通过乘以 255（反射带）或减去 100（热带）并四舍五入到最接近的整数来转换为 uint8
var composite = ee.Algorithms.Landsat.simpleComposite({
  collection: landsatCollection,
  asFloat: true
});

//将三个几何图层合并为一个 FeatureCollection。
var newfc = urban.merge(vegetation).merge(water);

// 使用这些波段进行分类。
var bands = ['B2', 'B3', 'B4', 'B5', 'B6', 'B7'];
// 存储类标签的点上的属性名称。
var classProperty = 'landcover';

//对组合进行采样以生成训练数据。请注意，类标签存储在 'landcover' 属性中。
//将与一个或多个区域相交的图像的每个像素（以给定比例）转换为特征，并将它们作为 FeatureCollection 返回。每个输出要素将具有输入图像的每个波段的一个属性，以及从输入要素复制的任何指定属性。请注意，几何图形将捕捉到像素中心。
var training = composite.select(bands).sampleRegions({
  collection: newfc,
  properties: [classProperty],
  scale: 30
});

// 训练 CART 分类器。
var classifier = ee.Classifier.smileCart().train({
  features: training,
  classProperty: classProperty,
});
// 
打印一些关于分类器的信息（特定于 CART）。
print('CART, explained', classifier.explain());

//对组合进行分类。
var classified = composite.classify(classifier);
Map.centerObject(newfc);
Map.addLayer(classified, {min: 0, max: 2, palette: ['red', 'green', 'blue']});

// 做一些准确性评估。首先，向训练数据集中添加一列随机。
var withRandom = training.randomColumn('random');

// 我们希望保留一些数据用于测试，以避免过度拟合模型。
var split = 0.7;  // 大约 70% 的训练，30% 的测试。
var trainingPartition = withRandom.filter(ee.Filter.lt('random', split));
var testingPartition = withRandom.filter(ee.Filter.gte('random', split));

// 使用我们 70% 的数据进行训练。
var trainedClassifier = ee.Classifier.smileRandomForest(5).train({
  features: trainingPartition,
  classProperty: classProperty,
  inputProperties: bands
});

// 对测试 FeatureCollection 进行分类。
var test = testingPartition.classify(trainedClassifier);

// Print the confusion matrix.
var confusionMatrix = test.errorMatrix(classProperty, 'classification');
print('Confusion Matrix', confusionMatrix);