Combining FeatureCollections

  • This tutorial demonstrates how to combine two ee.FeatureCollection objects in Google Earth Engine into a new, single ee.FeatureCollection.

  • The tutorial uses randomly generated points within a specified geometry (Utah) as an example dataset.

  • Users learn to visualize the original and combined ee.FeatureCollections on a map with custom colors and labels.

  • The tutorial provides a basic framework for merging feature collections, applicable to various geospatial data analysis tasks.

  • Bonus points encourage users to experiment with map visualization and layer customization for enhanced understanding.
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Author(s): sabrinaszeto
This basic tutorial shows how users can combine two ee.FeatureCollections into a new ee.FeatureCollection.

Create two ee.FeatureCollection objects

Let's begin by generating two sets of random points within the boundary of Utah state in the USA. First, define the boundary of Utah as a geometry.

var utahGeometry = ee.Geometry.Polygon([
  [-114.05, 37],
  [-109.05, 37],
  [-109.05, 41],
  [-111.05, 41],
  [-111.05, 42],
  [-114.05, 42]
]);

Then, generate two sets of different random points containing 25 points each. We ensure that the points are different by using a different seed, namely 12 and 1, to generate each set.

var newFeatures = ee.FeatureCollection.randomPoints(utahGeometry, 25, 12);
var moreNewFeatures = ee.FeatureCollection.randomPoints(utahGeometry, 25, 1);

Combine the ee.FeatureCollection objects

Next, create a new ee.FeatureCollection by merging newFeatures and moreNewFeatures.

var combinedFeatureCollection = newFeatures.merge(moreNewFeatures);

Visualize the Results

Let's add all the ee.FeatureCollections to the map. First, we set the center of the map to the coordinates defined below and set the zoom level to 6.

Map.setCenter(-111.445, 39.251, 6);

Now, we add all the layers, specifying the layer labels as text strings (for example, 'New Features') and colors to display each layer in. We will also print the results.

Map.addLayer(newFeatures, {}, 'New Features');
Map.addLayer(moreNewFeatures, {color: 'red'}, 'More New Features');
Map.addLayer(combinedFeatureCollection, {color: 'yellow'}, 'Combined FeatureCollection');

print(newFeatures, moreNewFeatures, combinedFeatureCollection);

Bonus Points

  • What happens if you change the zoom level in Map.setCenter to 3 or to 12?
  • Try changing the layer label of 'More New Features' to 'Red Points'. Run the script again to see if it worked.