Page Summary
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FeatureCollection.flatten() is used to flatten collections of collections.
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The method takes a FeatureCollection as input and returns a flattened FeatureCollection.
| Usage | Returns |
|---|---|
FeatureCollection.
flatten
()
|
FeatureCollection |
| Argument | Type | Details |
|---|---|---|
|
this:
collection
|
FeatureCollection | The input collection of collections. |
Examples
Code Editor (JavaScript)
// Counties in New Mexico, USA. var counties = ee . FeatureCollection ( 'TIGER/2018/Counties' ) . filter ( 'STATEFP == "35"' ); // Monthly climate and climatic water balance surfaces for January 2020. var climate = ee . ImageCollection ( 'IDAHO_EPSCOR/TERRACLIMATE' ) . filterDate ( '2020-01' , '2020-02' ); // Calculate mean climate variables for each county per climate surface // time step. The result is a FeatureCollection of FeatureCollections. var countiesClimate = climate . map ( function ( image ) { return image . reduceRegions ({ collection : counties , reducer : ee . Reducer . mean (), scale : 5000 , crs : 'EPSG:4326' }); }); // Note that a printed FeatureCollection of FeatureCollections is not // recursively expanded, you cannot view metadata of the features within the // nested collections until you isolate a single collection or flatten the // collections. print ( 'FeatureCollection of FeatureCollections' , countiesClimate ); print ( 'Flattened FeatureCollection of FeatureCollections' , countiesClimate . flatten ());
import ee import geemap.core as geemap
Colab (Python)
# Counties in New Mexico, USA. counties = ee . FeatureCollection ( 'TIGER/2018/Counties' ) . filter ( 'STATEFP == "35"' ) # Monthly climate and climatic water balance surfaces for January 2020. climate = ee . ImageCollection ( 'IDAHO_EPSCOR/TERRACLIMATE' ) . filterDate ( '2020-01' , '2020-02' ) # Calculate mean climate variables for each county per climate surface # time step. The result is a FeatureCollection of FeatureCollections. def reduce_mean ( image ): return image . reduceRegions ( ** { 'collection' : counties , 'reducer' : ee . Reducer . mean (), 'scale' : 5000 , 'crs' : 'EPSG:4326' }) counties_climate = climate . map ( reduce_mean ) # Note that a printed FeatureCollection of FeatureCollections is not # recursively expanded, you cannot view metadata of the features within the # nested collections until you isolate a single collection or flatten the # collections. display ( 'FeatureCollection of FeatureCollections:' , counties_climate ) display ( 'Flattened FeatureCollection of FeatureCollections:' , counties_climate . flatten ())
