ee.FeatureCollection.flatten

Flattens collections of collections.
UsageReturns
FeatureCollection.flatten()FeatureCollection
ArgumentTypeDetails
this: collectionFeatureCollectionThe 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 2020.
var climate = ee.ImageCollection('IDAHO_EPSCOR/TERRACLIMATE')
                  .filterDate('2020-01', '2020-04');

// 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());