驚喜疑羞 2021-08-15 22:34:28 阅读数:245
var gfc2020 = ee.Image("UMD/hansen/global_forest_change_2020_v1_8")
Map.addLayer(gfc2020, {bands: ['treecover2000']}, 'Tree cover in 2000')
Map.addLayer(gfc2020, {bands: ['last_b50', 'last_b40', 'last_b30']}, 'False colour')
Map.addLayer(gfc2020, {bands: ['loss', 'treecover2000', 'gain']}, 'Green')
Map.addLayer(gfc2020, {
bands: ['loss', 'treecover2000', 'gain'],
max: [1, 255, 1]
}, 'Forest cover, loss, gain')
Map.addLayer(gfc2020, {
bands: ['treecover2000'],
palette: ['000000', '00FF00']
}, 'Forest cover palette')
Map.addLayer(gfc2020, {
bands: ['treecover2000'],
palette: ['000000', '00FF00'],
max: 100
}, 'Forest cover percent')
Map.addLayer(gfc2020.mask(gfc2020), {
bands: ['treecover2000'],
palette: ['000000', '00FF00'],
max: 100
}, 'Forest cover masked')
var treeCover = gfc2020.select(['treecover2000']);
var lossImage = gfc2020.select(['loss']);
var gainImage = gfc2020.select(['gain']);
// 綠色代錶森林覆蓋
Map.addLayer(treeCover.updateMask(treeCover),
{palette: ['000000', '00FF00'], max: 100}, 'Forest Cover')
// 紅色代錶損失
Map.addLayer(lossImage.updateMask(lossImage),
{palette: ['FF0000']}, 'Loss')
// 藍色代錶增益
Map.addLayer(gainImage.updateMask(gainImage),
{palette: ['0000FF']}, 'Gain')
// 從LSIB數據集加載國家邊界
var countries = ee.FeatureCollection('USDOS/LSIB_SIMPLE/2017')
// 根據代碼找到馬來西亞
var malay = countries.filter(ee.Filter.eq('country_co', 'MY'))
// 獲取損失圖像
var lossImage = gfc2020.select(['loss'])
var lossAreaImage = lossImage.multiply(ee.Image.pixelArea())
var lossYear = gfc2020.select(['lossyear'])
var lossByYear = lossAreaImage.addBands(lossYear).reduceRegion({
reducer: ee.Reducer.sum().group({
groupField: 1
}),
geometry: malay,
scale: 30,
maxPixels: 1e9
})
print(lossByYear)
var statsFormatted = ee.List(lossByYear.get('groups'))
.map(function(el) {
var d = ee.Dictionary(el);
return [ee.Number(d.get('group')).format("20%02d"), d.get('sum')]
})
var statsDictionary = ee.Dictionary(statsFormatted.flatten())
print(statsDictionary)
var chart = ui.Chart.array.values({
array: statsDictionary.values(),
axis: 0,
xLabels: statsDictionary.keys()
}).setChartType('ColumnChart')
.setOptions({
title: 'Yearly Forest Loss',
hAxis: {title: 'Year', format: '####'},
vAxis: {title: 'Area (square meters)'},
legend: { position: "none" },
lineWidth: 1,
pointSize: 3
})
print(chart)
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