ee.FeatureCollection.merge

  • FeatureCollection.merge() combines two FeatureCollections into a single FeatureCollection containing all elements from both.

  • Elements from the input collections retain their original properties but are given new IDs prefixed with "1*" and "2*" to distinguish their source.

  • For merging multiple collections, using FeatureCollection.flatten() on a collection containing all of them is recommended for better performance.

  • Repeatedly using FeatureCollection.merge() can lead to decreased performance and excessively long element IDs.

 Merges two collections into one. The result has all the elements that were in either collection.

Elements from the first collection will have IDs prefixed with "1" and elements from the second collection will have IDs prefixed with "2".

UsageReturns
FeatureCollection.merge(collection2)FeatureCollection
ArgumentTypeDetails
this: collection1FeatureCollectionThe first collection to merge.
collection2FeatureCollectionThe second collection to merge.

Examples

Code Editor (JavaScript)

// FeatureCollection of points representing forest cover.
var fcForest = ee.FeatureCollection([
  ee.Feature(ee.Geometry.Point([-122.248, 37.238]),
             {'id': 0, 'cover_class': 'forest'}),
  ee.Feature(ee.Geometry.Point([-122.204, 37.222]),
             {'id': 1, 'cover_class': 'forest'}),
  ee.Feature(ee.Geometry.Point([-122.110, 37.199]),
             {'id': 2, 'cover_class': 'forest'})
]);

// FeatureCollection of points representing urban cover.
var fcUrban = ee.FeatureCollection([
  ee.Feature(ee.Geometry.Point([-121.953, 37.372]),
             {'id': 0, 'cover_class': 'urban'}),
  ee.Feature(ee.Geometry.Point([-121.861, 37.308]),
             {'id': 1, 'cover_class': 'urban'}),
  ee.Feature(ee.Geometry.Point([-121.984, 37.372]),
             {'id': 2, 'cover_class': 'urban'})
]);

// Merge the two FeatureCollections into one.
var fcMerged = fcForest.merge(fcUrban);

// Display FeatureCollections on the map.
Map.setCenter(-122.034, 37.296, 11);
Map.addLayer(fcForest, {color: 'green'}, 'Forest points');
Map.addLayer(fcUrban, {color: 'grey'}, 'Urban points');
Map.addLayer(fcMerged, {color: 'yellow'}, 'Protected areas merged');

Python setup

See the Python Environment page for information on the Python API and using geemap for interactive development.

import ee
import geemap.core as geemap

Colab (Python)

# FeatureCollection of points representing forest cover.
fc_forest = ee.FeatureCollection([
    ee.Feature(
        ee.Geometry.Point([-122.248, 37.238]),
        {
            'id': 0,
            'cover_class': 'forest',
            'id': 0,
            'cover_class': 'forest',
        },
    ),
    ee.Feature(
        ee.Geometry.Point([-122.204, 37.222]),
        {
            'id': 1,
            'cover_class': 'forest',
            'id': 1,
            'cover_class': 'forest',
        },
    ),
    ee.Feature(
        ee.Geometry.Point([-122.110, 37.199]),
        {
            'id': 2,
            'cover_class': 'forest',
            'id': 2,
            'cover_class': 'forest',
        },
    ),
])

# FeatureCollection of points representing urban cover.
fc_urban = ee.FeatureCollection([
    ee.Feature(
        ee.Geometry.Point([-121.953, 37.372]),
        {'id': 0, 'cover_class': 'urban', 'id': 0, 'cover_class': 'urban'},
    ),
    ee.Feature(
        ee.Geometry.Point([-121.861, 37.308]),
        {'id': 1, 'cover_class': 'urban', 'id': 1, 'cover_class': 'urban'},
    ),
    ee.Feature(
        ee.Geometry.Point([-121.984, 37.372]),
        {'id': 2, 'cover_class': 'urban', 'id': 2, 'cover_class': 'urban'},
    ),
])

# Merge the two FeatureCollections into one.
fc_merged = fc_forest.merge(fc_urban)

# Display FeatureCollections on the map.
m = geemap.Map()
m.set_center(-122.034, 37.296, 11)
m.add_layer(fc_forest, {'color': 'green'}, 'Forest points')
m.add_layer(fc_urban, {'color': 'grey'}, 'Urban points')
m.add_layer(fc_merged, {'color': 'yellow'}, 'Protected areas merged')
m