My raster file has 29 classes and I applied 'Reclassify by table' in QGIS 3.16 to assign 1 to classes 15 and 24 only and all other classes were classified as 0. I applied the following script to polygonize these two classes which works fine without the reclassify part.

 var image = ee.Image("users/parivash89/verceli_tiles_3")
 var oldgroup = ee.List([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]);
 var newgroup = ee.List([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0]);

    Map.addLayer(newgroup );
    Map.centerObject(newgroup );
    var classes = newgroup .reduceToVectors({
      reducer: ee.Reducer.countEvery(), 
      scale: 10,
      maxPixels: 1e10
    var result = ee.FeatureCollection(classes);
    // Export the FeatureCollection to a SHP file.
      collection: result,
      folder: 'GEE_Polygonize',
      fileFormat: 'SHP'

But when I add the reclasify part, I get this error:

Cannot add an object of type <List> to the map.
    in <global>, line 67
    in <global>, line 83

What should I add to choose the selected classes only and polygonize only them?

  • 1
    Please provide complete example which reproduces the error you mention. As of now, newgroup is not defined.
    – kkrao
    Apr 8, 2021 at 7:22
  • Thanks @kkrao, I thought I defined it by indicating the var newgroup. Maybe that is my error. I changed the code as I run it in the question
    – Paris
    Apr 8, 2021 at 14:10
  • 1
    I am still unable to reproduce your error. Please share the image asset (make it public). The current error is: Image (Error) Image.load: Image asset 'users/parivash89/verceli_tiles_3' not found.
    – kkrao
    Apr 9, 2021 at 16:06
  • Thanks @kkrao. I realized what was my mistake. I add my answer. Thanks for your help.
    – Paris
    Apr 12, 2021 at 8:14

1 Answer 1


Remap function was my answer since I was tring to operate on individual values. By adding these lines, the script was done:


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