ee.FeatureCollection.evaluate

  • evaluate() retrieves the value of a ComputedObject (like a FeatureCollection) from the Earth Engine server and passes it to a callback function.

  • The callback function is structured as function(success, failure) where success contains the result if the request succeeds, and failure contains an error message if it fails.

  • This method transfers data from the server to the client, potentially impacting performance; server-side options are generally preferred.

  • For asynchronous evaluation of ee.FeatureCollection in the Earth Engine Python client library, use getInfo() instead of evaluate().

Asynchronously retrieves the value of this object from the server and passes it to the provided callback function.

UsageReturns
FeatureCollection.evaluate(callback)
ArgumentTypeDetails
this: computedobjectComputedObjectThe ComputedObject instance.
callbackFunctionA function of the form function(success, failure), called when the server returns an answer. If the request succeeded, the success argument contains the evaluated result. If the request failed, the failure argument will contains an error message.

Examples

Code Editor (JavaScript)

/**
 * WARNING: this function transfers data from Earth Engine servers to the
 * client. Doing so can negatively affect request processing and client
 * performance. Server-side options should be used whenever possible.
 * Learn more about the distinction between server and client:
 * https://developers.google.com/earth-engine/guides/client_server
 */

// FeatureCollection of power plants in Belgium.
var fcServer = ee.FeatureCollection('WRI/GPPD/power_plants')
             .filter('country_lg == "Belgium"');

fcServer.evaluate(function(fcClient) {
  print('Client-side feature collection is an object', typeof fcClient);
  print('Feature collection object keys', Object.keys(fcClient));
  print('Array of features', fcClient.features);
  print('Properties for first feature', fcClient.features[0].properties);
});

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)

# The Earth Engine Python client library does not have an evaluate method for
# asynchronous evaluation of ee.FeatureCollection objects.
# Use ee.FeatureCollection.getInfo() instead.