The reducer must have the same number of inputs as the input image has bands.
Returns the input features, each augmented with the corresponding reducer outputs.
Usage | Returns |
---|---|
Image.reduceRegions(collection, reducer, scale, crs, crsTransform, tileScale) | FeatureCollection |
Argument | Type | Details |
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this: image | Image | The image to reduce. |
collection | FeatureCollection | The features to reduce over. |
reducer | Reducer | The reducer to apply. |
scale | Float, default: null | A nominal scale in meters of the projection to work in. |
crs | Projection, default: null | The projection to work in. If unspecified, the projection of the image's first band is used. If specified in addition to scale, rescaled to the specified scale. |
crsTransform | List, default: null | The list of CRS transform values. This is a row-major ordering of the 3x2 transform matrix. This option is mutually exclusive with 'scale', and will replace any transform already set on the projection. |
tileScale | Float, default: 1 | A scaling factor used to reduce aggregation tile size; using a larger tileScale (e.g. 2 or 4) may enable computations that run out of memory with the default. |
Examples
Code Editor (JavaScript)
// A Landsat 8 SR image with SWIR1, NIR, and green bands. var img = ee.Image('LANDSAT/LC08/C02/T1_L2/LC08_044034_20210508') .select(['SR_B6', 'SR_B5', 'SR_B3']); // Santa Cruz Mountains ecoregions feature collection. var regionCol = ee.FeatureCollection('EPA/Ecoregions/2013/L4') .filter('us_l4name == "Santa Cruz Mountains" || ' + 'us_l4name == "San Mateo Coastal Hills" || ' + 'us_l4name == "Leeward Hills"'); // Display layers on the map. Map.setCenter(-122.08, 37.22, 9); Map.addLayer(img, {min: 10000, max: 20000}, 'Landsat image'); Map.addLayer(regionCol, {color: 'white'}, 'Santa Cruz Mountains ecoregions'); // Calculate median band values within Santa Cruz Mountains ecoregions. It is // good practice to explicitly define "scale" (or "crsTransform") and "crs" // parameters of the analysis to avoid unexpected results from undesired // defaults when e.g. reducing a composite image. var stats = img.reduceRegions({ collection: regionCol, reducer: ee.Reducer.median(), scale: 30, // meters crs: 'EPSG:3310', // California Albers projection }); // The input feature collection is returned with new properties appended. // The new properties are the outcome of the region reduction per image band, // for each feature in the collection. Region reduction property names // are the same as the input image band names. print('Median band values, Santa Cruz Mountains ecoregions', stats); // You can combine reducers to calculate e.g. mean and standard deviation // simultaneously. The resulting property names are the concatenation of the // band names and statistic names, separated by an underscore. var reducer = ee.Reducer.mean().combine({ reducer2: ee.Reducer.stdDev(), sharedInputs: true }); var multiStats = img.reduceRegions({ collection: regionCol, reducer: reducer, scale: 30, crs: 'EPSG:3310', }); print('Mean & SD band values, Santa Cruz Mountains ecoregions', multiStats);