ee.Geometry.MultiPolygon.difference

  • difference() returns a Geometry representing the portion of the 'left' geometry that does not intersect with the 'right' geometry.

  • This method can be used with MultiPolygon geometries to find the areas where they do not overlap with another geometry.

  • Optional parameters include maxError for reprojection tolerance and proj for specifying the projection.

  • The result of this operation can be used in further geospatial analysis or visualization.

Returns the result of subtracting the 'right' geometry from the 'left' geometry.

UsageReturns
MultiPolygon.difference(right, maxError, proj)Geometry
ArgumentTypeDetails
this: leftGeometryThe geometry used as the left operand of the operation.
rightGeometryThe geometry used as the right operand of the operation.
maxErrorErrorMargin, default: nullThe maximum amount of error tolerated when performing any necessary reprojection.
projProjection, default: nullThe 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 difference method to the MultiPolygon object.
var multiPolygonDifference = multiPolygon.difference({'right': inputGeom, 'maxError': 1});

// Print the result to the console.
print('multiPolygon.difference(...) =', multiPolygonDifference);

// 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(multiPolygonDifference,
             {'color': 'red'},
             'Result [red]: multiPolygon.difference');

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 difference method to the MultiPolygon object.
multipolygon_difference = multipolygon.difference(right=input_geom, maxError=1)

# Print the result.
display('multipolygon.difference(...) =', multipolygon_difference)

# 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_difference,
    {'color': 'red'},
    'Result [red]: multipolygon.difference',
)
m