Google Earth Engine（GEE）——ImageCollection.fromImages, argument ‘images‘: Invalid type. Expected type

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.

Arguments:

this:collection (FeatureCollection):

The input collection of collections.

Returns: FeatureCollection

flatten()

Flattens any sublists into a single list.

Arguments:

this:list (List)

Returns: 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  )