ee.FeatureCollection.map

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Examples

Maps an algorithm over a collection.

Returns the mapped collection.

Usage	Returns
`FeatureCollection.map(algorithm, dropNulls)`	Collection

Argument	Type	Details
this: `collection`	Collection	The Collection instance.
`algorithm`	Function	The operation to map over the images or features of the collection. A JavaScript function that receives an image or features and returns one. The function is called only once and the result is captured as a description, so it cannot perform imperative operations or rely on external state.
`dropNulls`	Boolean, optional	If true, the mapped algorithm is allowed to return nulls, and the elements for which it returns nulls will be dropped.

Examples

Code Editor (JavaScript)Colab (Python)

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

// Function to convert power plant capacity from megawatts to gigawatts and
// add the value as a new feature property.
var mwToGw = function(feature) {
  var megawatt = feature.getNumber('capacitymw');
  var gigawatt = megawatt.divide(1000);
  return feature.set('capacitygw', gigawatt);
};

// Apply the function to each feature in the collection.
fc = fc.map(mwToGw);

print('Note the new "capacitygw" property in each feature', fc);

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

# FeatureCollection of power plants in Belgium.
fc = ee.FeatureCollection('WRI/GPPD/power_plants').filter(
    'country_lg == "Belgium"')

# Function to convert power plant capacity from megawatts to gigawatts and
# add the value as a new feature property.
def mw_to_gw(feature):
  megawatt = feature.getNumber('capacitymw')
  gigawatt = megawatt.divide(1000)
  return feature.set('capacitygw', gigawatt)

# Apply the function to each feature in the collection.
fc = fc.map(mw_to_gw)

print('Note the new "capacitygw" property in each feature:', fc.getInfo())