当我们遇到下面问题时,我们就是可能嵌套类型太多了,所以我们需要去掉原有的括号,也就是括号嵌套太多了,所以我们用在打印list时我们就需要脱掉外面的一层括号,这样才能正确展示,这里我们首先看看错误提示
错误:
ImageCollection (Error)
ImageCollection.fromImages, argument 'images': Invalid type.
Expected type: List<Image<unknown bands>>.
Actual type: List<List<Image<[LST_Day_1km]>>>. Actual value: [[<Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>], [<Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>], [<Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>], [<Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>], [<Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>, <Image<[LST_Day_1km]>>]]
原始代码:
var ROI = ee.FeatureCollection("projects/geemijan/assets/Bangladesh");
var modis = ee.ImageCollection("MODIS/006/MOD11A2")
.select('LST_Day_1km')
.filterDate('2012-01-01','2016-12-31')
.filterBounds(ROI)
Map.setOptions('SATELLITE')
Map.addLayer(ROI)
Map.centerObject(ROI,5)
var LST_Res = function(image){
var LST_temp = image.toFloat().multiply(0.02).subtract(273.15)
image = image.addBands(LST_temp);
return image;
}
var LST_new = modis.map(LST_Res)
var modis = LST_new.select('LST_Day_1km')
.map(function(img){
var d = ee.Date(ee.Number(img.get('system:time_start')));
var m = ee.Number(d.get('month'));
var y = ee.Number(d.get('year'));
return img.set({'month':m, 'year':y})
})
print(modis)
var months = ee.List.sequence(1,12)
var years = ([2012, 2013, 2014, 2015, 2016])
var byYearMonth = ee.ImageCollection.fromImages(
years.map(function(y){
return months.map(function(m){
return modis.filterMetadata('year','equals',y)
.filterMetadata('month','equals',m)
.select('LST_Day_1km').mean()
.set('year',y)
.set('month',m)
.set('date', ee.Date.fromYMD(y,m,1))
});
})
)
print( byYearMonth )
此处的需要一个函数:
flatten()
Flattens collections of collections.
this:collection (FeatureCollection):
The input collection of collections.
flatten()
Flattens any sublists into a single list.
this:list (List)
修改后的代码:
var modis = ee.ImageCollection("MODIS/006/MOD11A2")
.select('LST_Day_1km')
.filterDate('2012-01-01','2016-12-31')
.filterBounds(ROI)
Map.setOptions('SATELLITE')
Map.addLayer(ROI)
Map.centerObject(ROI,5)
var LST_Res = function(image){
var LST_temp = image.toFloat().multiply(0.02).subtract(273.15)
image = image.addBands(LST_temp);
return image;
}
var LST_new = modis.map(LST_Res)
var modis = LST_new.select('LST_Day_1km')
.map(function(img){
var d = ee.Date(ee.Number(img.get('system:time_start')));
var m = ee.Number(d.get('month'));
var y = ee.Number(d.get('year'));
return img.set({'month':m, 'year':y})
})
print(modis)
var months = ee.List.sequence(1,12)
// var years = ([2012, 2013, 2014, 2015, 2016]
var years = ee.List.sequence(2012,2016)
var byYearMonth = ee.ImageCollection.fromImages(
years.map(function(y){
return months.map(function(m){
return modis.filterMetadata('year','equals',y)
.filterMetadata('month','equals',m)
.select('LST_Day_1km').mean()
.set('year',y)
.set('month',m)
.set('date', ee.Date.fromYMD(y,m,1))
});
}).flatten()
)
print( byYearMonth )