Google Earth Engine学习笔记（三） GEE

Google Earth Engine学习笔记（三）

原文
翻译
代码
翻译
结果

Day-Of-Year (DOY) Charts（年度（DOY）图表）
原文 The methods that start with ui.Chart.image.doySeries aggregate the time series by day-of-year (DOY). The plots can be created as a DOY average, by year, or by region. The following example uses MODIS NDVI time series to illustrate different modes of DOY charting:
翻译方法ui.Chart.image.doySeries可以按年度（DOY）汇总时间序列。这些图可以按年份或按地区划分为DOY平均值。以下示例使用MODIS NDVI时间序列来说明DOY图表的不同模式：
代码

// Define a FeatureCollection: three regions of the American West. var city = ee.Feature(// San Francisco. ee.Geometry.Rectangle(-122.42, 37.78, -122.4, 37.8), {label: 'City'}); var forest = ee.Feature(// Tahoe National Forest. ee.Geometry.Rectangle(-121, 39.4, -120.99, 39.45), {label: 'Forest'}); var desert = ee.Feature(// Black Rock Desert. ee.Geometry.Rectangle(-119.02, 40.95, -119, 41), {label: 'Desert'}); var regions = new ee.FeatureCollection([city, forest, desert]); // Load several years of MODIS NDVI data. var collection = ee.ImageCollection('MODIS/MCD43A4_006_NDVI') .filterDate(ee.Date('2011-01-01'), ee.Date('2014-12-31')); // Define a chart with one series in the forest region, averaged by DOY. var series1 = ui.Chart.image.doySeries( collection, forest, ee.Reducer.mean(), 500); // Define a chart with a different series for each year in the forest region. var series2 = ui.Chart.image.doySeriesByYear( collection, 'NDVI', forest, ee.Reducer.mean(), 500); // Define a chart with different series for each region, averaged by DOY. var series3 = ui.Chart.image.doySeriesByRegion( collection, 'NDVI', regions, ee.Reducer.mean(), 500, ee.Reducer.mean(), 'label'); // Display the three charts. print(series1, series2, series3);

翻译结果应如图1所示。图1中的顶部图表代表DOY的平均NDVI时间序列。中间的图表在输入图像中绘制了每年不同的系列。底部图表为输入中的每个区域绘制了不同的系列。观察需要在ui.Chart.image.doySeriesByYear（）和ui.Chart.image.doySeriesByRegion（）中指定要绘制的波段名称。使用ui.Chart.image.doySeriesByRegion（）时，需要指定区分不同区域的要素（标签）的属性。在所有情况下，示例使用默认的ee.Reducer.mean（）来临时（通过DOY）和空间（按区域）聚合。
结果