Calculating area of different classes in Google Earth Engine

Question

I am trying to classify the India into forest, agriculture and urban areas using Google Earth Engine, but after classification I am trying to calculate areas of classes like this:

var im=l8.filterDate('2018-01-01','2018-12-31');
var cloudless =im.map(function(image) {
  var cloudy = ee.Algorithms.Landsat.simpleCloudScore(image).select('cloud');
  var mask = cloudy.lte(20)
  return image.updateMask(mask);
});
var cld=cloudless.median();
var cloud=cld.clipToCollection(ind);

do the classification:

var classNames=urban.merge(forest).merge(agriculture).merge(water);
var bands = ['B2', 'B3', 'B4', 'B5', 'B6', 'B7'];
var training = cloud.select(bands).sampleRegions({
 collection: classNames
properties: ['landcover'],
scale: 30
});
var classifier = ee.Classifier.randomForest().train({
 features: training,
 classProperty: 'landcover',
 inputProperties: bands
});
var classified = cloud.select(bands).classify(classifier);
Map.addLayer(classified,{min: 0, max: 3, palette: ['red', 'green', 'yellow','blue']},'classification');

Calculate the area of different classes

var names = ['urb','for','agri','watr']
var count = classified.eq([0,1,2,3]).rename(names);
var total = count.multiply(ee.Image.pixelArea());
var area = total.reduceRegion({
 reducer:ee.Reducer.sum(),
  geometry:ind,
  scale:30,
 maxPixels: 1e9,
 bestEffort:true
});
var area_pxa = ee.Number(area).divide(1e6)
print ('Area in (km²):', area_pxa)

When I am running this, it is taking a lot of time and showing error:

computation timed out.

How to overcome this error?

Here is the link to my code:https://code.earthengine.google.com/08783af235d2672177f2af9f1d81e714

Answer 1

The computation is too large (scale, extent, complexity, etc) to complete in the roughly 5 minutes that a request is allowed when working interactively in the Code Editor.

You could try to export your classification as an asset, before calculating the areas. Include something like this in your script:

Export.image.toAsset({
  image: classified,
  description: 'my_classification',
  scale: 30,
  pyramidingPolicy: {'.default': 'mode'}
})

Go to the "Tasks" section on the right hand side, and select 'Run'. Look at the docs for more details on how to do the export (https://developers.google.com/earth-engine/exporting). Once your task completes, you can import your classification and do further processing on it.

var classified = ee.Image('users/yourUserName/my_classification')