Thursday, 29 December 2016

javascript - Earth Engine convert list with coordinates and values into a feature collection for export


I need to create a feature collection from a list containing coordinates and band values. These are extracted from a landsat image as shown in this linked script.


Extract complete pixel values inside a geometry


I'm unable to find a solution in creating a feature collection. Here is the tail end code.


var valuesList = joinedImage.reduceRegion({
reducer: ee.Reducer.toList(4),
geometry: myGeometry
}).values().get(0);


var feature = ee.Feature(null, valuesList);


// Wrap the Feature in a FeatureCollection for export.
var myFeatures = ee.FeatureCollection([feature]);


// Export the image, specifying scale and region.
Export.table.toDrive(myFeatures,
"data",

"myData",
"B4-B5",
"CSV");

This doesn't work, because it is clearly the wrong way to create the feature collection. I've tried to create it similar to Rodrigo E. Principe's solution of mapping a Feature Collection but I can't seem to create the initial feature collection to start with.



Answer



valuesList = ee.List(valuesList) // Cast valuesList

var myFeatures = ee.FeatureCollection(valuesList.map(function(el){
el = ee.List(el) // cast every element of the list

var geom = ee.Geometry.Point([ee.Number(el.get(0)), ee.Number(el.get(1))])
return ee.Feature(geom, {'B4':ee.Number(el.get(2)), 'B5':ee.Number(el.get(3))})
}))

Map.addLayer(myFeatures) // see the result
Map.centerObject(myFeatures)

// Export the image, specifying scale and region.
Export.table.toDrive(myFeatures,
"data",

"myData",
"B4-B5",
"CSV");

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