Capture monthly yearly change temperature from CSV in GEE

Question

I did not receive any data from change temperature CSV from my code. How can I correct it?

I need to export monthly yearly change temperature in single CSV but I did not receive any data in my CSV.

How can I solve it?

//var regions = table.filterBounds(geometry);
var regionNames = ee.List([
  '1','2','3','4','5','6','7','8','9','10','11','12','13'
  ,'14','15','16','17','18','19','20','21','22'
]);
var regions = table.filterBounds(geometry)
  .map(function (region) {
    var index = region.getNumber('FID_1');
    return ee.Feature(region.geometry(), {
      'Region ID': index,
      'Region Name': regionNames.get(index)
    });
  });
  
Map.addLayer(regions);
var clipToCol = function(image){
  return image.clip(regions);
};
var change_c = ee.ImageCollection('MODIS/061/MOD11A2')
.filterDate(ee.Date('2001-01-01'), ee.Date('2022-01-01'))
.filterBounds(geometry)
.map(clipToCol);


var months = ee.List.sequence(1, 12);
var years = ee.List.sequence(2001, 2022);

var change= change_c.map(function(image) {
  return image.multiply(0.02).copyProperties(image,['system:time_start']);
});

var changeByMonthYear = ee.ImageCollection.fromImages(
  years.map(function(y) {
    return months.map(function (m) {
       var median = change
      return change
        .filter(ee.Filter.calendarRange(y, y, 'year'))
        .filter(ee.Filter.calendarRange(m, m, 'month'))
        .median()
        .set('month', m).set('year', y);
         return median
        .set('empty',  median.bandNames().size().eq(0));
  });
}).flatten());
var selectors = ['Region ID', 'Region Name', 'year', 'month', 'ndvi'];

var byRegion = changeByMonthYear
  .filter(ee.Filter.eq('empty', 0)) // Remove year/month without imagery
  .map(function(yearMonthchange) {
    return yearMonthchange
      .reduceRegions({
        collection: regions,
        reducer: ee.Reducer.median().setOutputs(['changetemp']), 
        scale: 500
        
      })
      .map(function (feature) {
        return feature
          .copyProperties(yearMonthchange, yearMonthchange.propertyNames());
      });
  })
  .flatten()
  .select(selectors);
Export.table.toDrive({
  collection: byRegion,
  description: 'changetemp',
  selectors: ['region', 'year', 'month', 'changetemp']
});

This is my link code: https://code.earthengine.google.com/13515dc5d295ecd2a3e3bdf2e495adab

Answer 1

The problem is that the empty property isn't set on the median images, but it's still used to filter out images. That leads to all images being filtered out. You probably want it to look like this:

  var median = change
    .filter(ee.Filter.calendarRange(y, y, 'year'))
    .filter(ee.Filter.calendarRange(m, m, 'month'))
    .median()
    .set('month', m).set('year', y)
  return median
    .set('empty', median.bandNames().size().eq(0))

https://code.earthengine.google.com/8767a223b0a8f6dc67042122c860762d