VIIRS Night lights

// define the countries of interest in this list
var countryList = ["Cambodia","Vietnam","Laos","Burma","Thailand"];
// import the country boundaries and filter for the countries of interest
var countries = ee.FeatureCollection('USDOS/LSIB_SIMPLE/2017').filter(ee.Filter.inList("country_na", countryList));
// add the layer to the map
Map.addLayer(countries,{},"countries of interest");

// import the nightlight image collection
var nightlight = ee.ImageCollection("NOAA/VIIRS/DNB/MONTHLY_V1/VCMSLCFG");

// set the start and end dates
var start = ee.Date.fromYMD(2014,1,1);
var end = ee.Date.fromYMD(2014,12,31);

// filter for the period of interest
var nightlights2014 = nightlight.filterDate(start,end);
// take the mean note that this operation transforms the image collection into an image
nightlights2014 = ee.Image(nightlights2014.mean());
// select the avg_rad band
nightlights2014 = nightlights2014.select("avg_rad");
// clip for the area of interest
nightlights2014 = nightlights2014.clip(countries);
Map.addLayer(nightlights2014,{min:0,max:10,palette:['000000','700000','808080','FFFF00','ffffff','ffffff','ffffff']},"nightlights 2014");

// set the start and end dates
var start = ee.Date.fromYMD(2021,1,1);
var end = ee.Date.fromYMD(2021,12,31);

// filter for the period of interest
var nightlights2021 = nightlight.filterDate(start,end);
// take the mean note that this operation transforms the image collection into an image
nightlights2021 = ee.Image(nightlights2021.mean());
// select the avg_rad band
nightlights2021 = nightlights2021.select("avg_rad");
// clip for the area of interest
nightlights2021 = nightlights2021.clip(countries);
Map.addLayer(nightlights2021,{min:0,max:10,palette:['000000','700000','808080','FFFF00','ffffff','ffffff','ffffff']},"nightlights 2021");