Select features in feature collection where two properties are equal in Google Earth Engine (GEE)

feature-collectiongoogle-earth-engine

I feel like I am missing something basic here. I am looking to select only the features within a feature collection that have matching property values.

For example I would like to only select the second row where both fields have the exact same date (2019-08-09):

Field1date	Field2date
2019-08-09	2019-08-08
2019-08-09	2019-08-09
2019-08-09	2019-08-10
2019-08-10	2019-08-08
2019-08-10	2019-08-09

If I export the feature collection from GEE to a .csv file I can do this simply with R with the following function:

datSelect<-data[data$Field1date==data$Field2date, ]

It would be great to do this before my Export.table.toDrive in GEE. I have tried with:

var datSelect = data.filterMetadata('Field1date', 'equals', 'Field2date');

But it returns zero elements.

Best Answer

Comparing field to field, you use the leftField, rightField arguments in ee.Filter.equals. (Also, you should basically never use filterMetadata)

data.filter(ee.Filter.equals({leftField: 'Field1date', rightField: 'Field2date'})

Related Solutions

Adding a column to a Google Earth Engine feature collection

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);

Get value of specific property in Earth Engine feature collection into a Python list

I found that on the feature collection fc the fc.aggregate_array() function does the trick, see Debugging Guide of Earth Engine and search for "Collection.map: A mapped algorithm must return a Feature or Image."

The code:

adm1_values_ee = country_subset.aggregate_array('ADM1_NAME') # returns an ee.ee_list.List
adm1_values = adm1_values_ee.getInfo() # turns the server-side object into a Python (client-side) list

The output is as expected: ['Western', 'Ashanti', ...]

Best Answer

Related Solutions

Adding a column to a Google Earth Engine feature collection

Get value of specific property in Earth Engine feature collection into a Python list

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