Hfrhyu

I have a set of points and I need to classify them according to which polygon they belong. The natural way of doing this is creating the intersections between all points and each polygon. The points have properties I want to keep and the intersection function requires me to have the polygon on the left side and I lose the properties of the input of the right side. How should I go about this? If I use the points on the left side it doesn't work.

https://code.earthengine.google.com/f7b34e63c5e9ad70f96e1ad91620d48a

I want an output that I can download as a .csv with each point, it's characteristics, and an indicator of the polygon they belong.

Code:

var p1 = ee.Feature(p1, id: 'id1');
var p2 = ee.Feature(p2, id: 'id2');
var p3 = ee.Feature(p3, id: 'id3');
var p4 = ee.Feature(p4, id: 'id4');

var points=ee.FeatureCollection([p1,p2,p3,p4]);
print(points,' points');

var cc1 = poly1.intersection(points, ee.ErrorMargin(1));
var cc2 = poly2.intersection(points, ee.ErrorMargin(1));

Map.addLayer(cc1,,'cc1');
Map.addLayer(cc2,,'cc2');

var ccs=ee.FeatureCollection([cc1,cc2]);
print(ccs,'ccs');

I think it's best practice to construct a feature collection of the points and a featuere collection of the polygons you have. Then map over both collections to calculate the intersection for every single point. You can hen add the properties to the existing properties of the feature and filter out the ones which did not intersect. Then export the feature collection as csv:

// Map over the feature collection of points so we 
// can inspect every single elements intersection and proprty
var ccs = points.map(function(feat)
 feat = ee.Feature(feat);
 var point = feat.geometry();
 // now map over the polygons
 var mappedPolys = polygons.map(function(poly)
 var intersects = poly.intersects(point, ee.ErrorMargin(1));
 // check if the point intersected with the polygon
 var property = ee.String(ee.Algorithms.If(intersects, poly.get('system:index'), 'FALSE'));
 // set a property to each individual feature
 return feat.set('belongsTo', ee.String('poly').cat(property))
 .set('pointID', ee.String('id').cat(ee.String(feat.get('system:index'))));
 );
 // return the point with the polygon they intersect with or a property called 'polyFALSE'
 return mappedPolys;
)
 // Flatten the collection of collections and filter out the 'polyFALSE' properties
 .flatten().filter(ee.Filter.neq('belongsTo', 'polyFALSE'));

link code