[GIS] How to filter image collection by date, excluding a date from a date range in Google Earth Engine

filtergoogle-earth-engine

I am using air surface temp data from 2015 in Google Earth Engine but there is missing data for June 19, 2015 which is assigned the value 9.9621e+36.

So I need to create a date range from Jan 1 2015 to Dec 31 2015 which excludes June 19 2015. I know how to filter by date:

var AST2015 = ee.ImageCollection('NCEP_RE/surface_temp')
                .filterDate('2015-01-01', '2015-12-31');

But as long as that one June date is in their my mean and other stats are ruined. SOS

Best Answer

You can remove images from an image collection by creating a date filter for the 'bad/missing' data and then remove it using ee.Filter.not(). For example:

var collection = ee.ImageCollection('NCEP_RE/surface_temp');
var AST2015 = collection.filterDate('2015-01-01', '2016-01-01');

var start_bad_data = '2015-06-18T00:00:00';
var end_bad_data = '2015-06-20T00:00:00';
var bad_data_filter = ee.Filter.date(start_bad_data, end_bad_data);

// Select the bad data.
var AST2015_bad_data = AST2015.filter(bad_data_filter);
// Select the good data.
var AST2015_good_data = AST2015.filter(bad_data_filter.not());

Map.addLayer(AST2015, {}, 'AST2015');
Map.addLayer(AST2015_bad_data, {}, 'AST2015_bad_data');
Map.addLayer(AST2015_good_data, {}, 'AST2015_good_data');

Your Code

These lines don't seem to work out:

var dateFilter = ee.ImageCollection(longRain2016.merge(shortRain2016).merge(longRain2017).merge(shortRain2017).merge(longRain2018));

var s2dateFilter = s2.filter(dateFilter);

You are trying to construct another ee.ImageCollection passing existing ImageCollections to it. According to the API, this won't work.

I also think that it is not necessary to achieve what you want because ee.ImageCollection.merge returns an ImageCollection anyway.

This should work:

var allSeasons = longRain2016.merge(shortRain2016).merge(longRain2017).merge(shortRain2017).merge(longRain2018);

Now, since you already should have a merged ImageCollection of all the seasons in allSeasons, you don't need the second step. (Actually this wouldn't work because your dateFilter object is not a Filter and filter() only accepts a Filter.)

You can simply proceed with var count = allSeasons.size();

Alternative way ("The Multiple-Filter-Method")

You could first create the Filters and then Filter.or()-join them together. Next you could apply this joint Filter to the ImageCollection:

//Create Filters
var longRain2016Filter = ee.Filter.date('2016-04-01','2016-05-31');
var shortRain2016Filter = ee.Filter.date('2016-11-15','2016-12-31');
var longRain2017Filter = ee.Filter.date('2017-04-01','2016-05-31');
var shortRain2017Filter = ee.Filter.date('2017-10-01','2016-12-31');
var longRain2018Filter = ee.Filter.date('2018-03-01','2018-05-31');

var allSeasonsFilter = ee.Filter.or(longRain2016Filter, shortRain2016Filter, longRain2017Filter, shortRain2017Filter, longRain2018Filter); // Create joint Filter

var allSeasons = s2.filter(allSeasonsFilter); //apply Filter to ImageCollection

Best Answer

Related Solutions

[GIS] Filter image collection with a date list in Google Earth Engine

Google Earth Engine Filter – Applying Multiple Date Filters in Google Earth Engine

Your Code

Alternative way ("The Multiple-Filter-Method")

Related Question