I am fairly new to Google Earth Engine. Essentially I am trying to export the mean temperature for each polygon in a the WDPA to a csv. I can export smaller subsections of the feature collection but if I try and do it for all the polygons the export fails with the following: Error: User Memory limit Exceeded
Is this possible or do i need to chop up the feature collection?
Thank you in advance!!
var wdpa = ee.FeatureCollection('WCMC/WDPA/current/polygons');
// Daily mean 2m air temperature
var dataset = ee.ImageCollection('ECMWF/ERA5/DAILY').select('mean_2m_air_temperature');
//Create a list of the years that you would like to take the mean for
var years = ee.List.sequence(1981,2018);
//Create an image collection that calculates the mean temperature for each year
var byYear = ee.ImageCollection.fromImages(
years.map(function (y) {
var year = dataset.filter(ee.Filter.date(ee.Date.fromYMD(y, 01, 01), ee.Date.fromYMD(y, 12, 31)))
.mean()
.set('year', ee.String('Year_').cat(ee.Number(y).int()));
return year;
}));
print(byYear);
// extract the mean temperature for each year in each protected area
var Mean_Temp = byYear.map(function(image) {
return image.reduceRegions({
// collection:wdpaCentroids,
collection: wdpa,
reducer: ee.Reducer.mean(),
scale: 1000
}).map(function(feature) {
var empty = feature.geometry();
return ee.Feature(null).set({
'wdpa_pid': ee.String(feature.get('WDPA_PID')),
'year': image.get('year'),
'temp_mean':feature.get('mean'),
'name': feature.get('NAME')
});
});
}).flatten();
// print(Mean_Temp);
// Format the triplet to allow for a CSV to be exported
var format = function(table, rowId, colId, rowProperty, colProperty) {
var rows = table.distinct(rowId);
var joined = ee.Join.saveAll('matches').apply({
primary: rows,
secondary: table,
condition: ee.Filter.equals({
leftField: rowId,
rightField: rowId
})
});
return joined.map(function(row) {
var values = ee.List(row.get('matches'))
.map(function(feature) {
feature = ee.Feature(feature);
return [feature.get(colId), feature.get(colProperty)];
}).flatten();
return row.select([rowId, rowProperty]).set(ee.Dictionary(values));
});
};
// Note that there's a dummy feature in there for the points ('null').
var transpose = format(Mean_Temp, 'wdpa_pid', 'year','null', 'temp_mean');
// print(transpose);
// Export the Dataset as a CSV
Export.table.toDrive({
collection: transpose,
description:'WDPA_Temperature',
fileFormat: "csv"
});
