Adding a column to a Google Earth Engine feature collection

Question

I am trying to generate a ground truth feature collection to do some machine learning. I have a shapefile that contains one class of my ground truth. and I am manually creating a second feature collection that contains the second class.

My shapefile contains 11 columns and 128 features. I would like to delete all the columns that are currently in the shapefile attribute table and add a column containing a constant number. This would allow me to later merge the shapefile with the feature collection I created to obtain a training set I can use for machine learning.

Is there a way to do this in GEE or should I edit the shapefile in QGIS and import it again?

Answer 1

To remove all the properties, use select() with an empty list of property names. Then you can add the class property and merge it with other collections, for classification or export:

// Replace these two collections with your uploaded shapefiles
var input_1 = ee.FeatureCollection([
  ee.Feature(ee.Geometry.Point(100, 10), { 'irrelevant': 123, }),
]);
var input_2 = ee.FeatureCollection([
  ee.Feature(ee.Geometry.Point(100, 20), { 'irrelevant': 456, }),
]);

var mergedWithClassesAdded =
  input_1.map(function (feature) {
    return feature.select([]).set('class', 1);
  })
  .merge(
    input_2.map(function (feature) {
      return feature.select([]).set('class', 2);
    })
  );

print(mergedWithClassesAdded);