ee.Geometry.MultiPolygon.union

AI-generated Key Takeaways

• The union method returns a Geometry representing the union of two geometries.

• It takes a right geometry as input, along with optional maxError and proj parameters for error handling and projection, respectively.

• The union operation combines the spatial extent of the input geometries into a single output geometry.

• This method can be applied to MultiPolygon objects, as demonstrated in the examples provided for JavaScript and Python.

Returns the union of the two geometries.

Usage	Returns
MultiPolygon.union(right, maxError, proj)	Geometry

Argument	Type	Details
this: left	Geometry	The geometry used as the left operand of the operation.
right	Geometry	The geometry used as the right operand of the operation.
maxError	ErrorMargin, default: null	The maximum amount of error tolerated when performing any necessary reprojection.
proj	Projection, default: null	The projection in which to perform the operation. If not specified, the operation will be performed in a spherical coordinate system, and linear distances will be in meters on the sphere.

Examples

Code Editor (JavaScript)

// Define a MultiPolygon object.
var multiPolygon = ee.Geometry.MultiPolygon(
    [[[[-122.092, 37.424],
       [-122.086, 37.418],
       [-122.079, 37.425],
       [-122.085, 37.423]]],
     [[[-122.081, 37.417],
       [-122.086, 37.421],
       [-122.089, 37.416]]]]);

// Define other inputs.
var inputGeom = ee.Geometry.BBox(-122.085, 37.415, -122.075, 37.425);

// Apply the union method to the MultiPolygon object.
var multiPolygonUnion = multiPolygon.union({'right': inputGeom, 'maxError': 1});

// Print the result to the console.
print('multiPolygon.union(...) =', multiPolygonUnion);

// Display relevant geometries on the map.
Map.setCenter(-122.085, 37.422, 15);
Map.addLayer(multiPolygon,
             {'color': 'black'},
             'Geometry [black]: multiPolygon');
Map.addLayer(inputGeom,
             {'color': 'blue'},
             'Parameter [blue]: inputGeom');
Map.addLayer(multiPolygonUnion,
             {'color': 'red'},
             'Result [red]: multiPolygon.union');

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)

# Define a MultiPolygon object.
multipolygon = ee.Geometry.MultiPolygon([
    [[
        [-122.092, 37.424],
        [-122.086, 37.418],
        [-122.079, 37.425],
        [-122.085, 37.423],
    ]],
    [[[-122.081, 37.417], [-122.086, 37.421], [-122.089, 37.416]]],
])

# Define other inputs.
input_geom = ee.Geometry.BBox(-122.085, 37.415, -122.075, 37.425)

# Apply the union method to the MultiPolygon object.
multipolygon_union = multipolygon.union(right=input_geom, maxError=1)

# Print the result.
display('multipolygon.union(...) =', multipolygon_union)

# Display relevant geometries on the map.
m = geemap.Map()
m.set_center(-122.085, 37.422, 15)
m.add_layer(
    multipolygon, {'color': 'black'}, 'Geometry [black]: multipolygon'
)
m.add_layer(input_geom, {'color': 'blue'}, 'Parameter [blue]: input_geom')
m.add_layer(
    multipolygon_union, {'color': 'red'}, 'Result [red]: multipolygon.union'
)
m