// บทเรียน Air Temperature  data by ECMWF Hand on 
// Code provided by Dr.Sitthisak Moukomla 

var c = ee.FeatureCollection('USDOS/LSIB_SIMPLE/2017').filter(ee.Filter.eq('country_na', 'Thailand'));
              //Map.addLayer(geometry);
var dataset = ee.ImageCollection('ECMWF/ERA5_LAND/MONTHLY_AGGR')
                .select('temperature_2m');
// Use ee.Filter.calendarRange to filter by year and month

var img = dataset.filter(ee.Filter.calendarRange(1981,2024,'year'))
.filter(ee.Filter.calendarRange(3,3,'month'));

// reduce image collection with mean()
var mean = img.median().subtract(273.15);

var vis = {
  bands: ['temperature_2m'],
  min: 10.0,
  max: 35.0,
  palette: [
    "#000080","#0000D9","#4000FF","#8000FF","#0080FF","#00FFFF",
    "#00FF80","#80FF00","#DAFF00","#FFFF00","#FFF500","#FFDA00",
    "#FFB000","#FFA400","#FF4F00","#FF2500","#FF0A00","#FF00FF",
  ]
};

Map.addLayer(mean.clip(c), vis, "Air temperature [K] at 2m height");

/*
 * Legend setup
 */
// Creates a color bar thumbnail image for use in legend from the given color
// palette.
function makeColorBarParams(palette) {
  return {
    bbox: [0, 0, 1, 0.1],
    dimensions: '100x10',
    format: 'png',
    min: 0,
    max: 1,
    palette: palette,
  };
}
// Create the color bar for the legend.
var colorBar = ui.Thumbnail({
  image: ee.Image.pixelLonLat().select(0),
  params: makeColorBarParams(vis.palette),
  style: {stretch: 'horizontal', margin: '0px 8px', maxHeight: '24px'},
});
// Create a panel with three numbers for the legend.
var legendLabels = ui.Panel({
  widgets: [
    ui.Label(vis.min, {margin: '4px 8px'}),
    ui.Label(
        (vis.max / 2),
        {margin: '4px 8px', textAlign: 'center', stretch: 'horizontal'}),
    ui.Label(vis.max, {margin: '4px 8px'})
  ],
  layout: ui.Panel.Layout.flow('horizontal')
});
var legendTitle = ui.Label({
  value: 'Map Legend: Air temperature [C] at 2m height',
  style: {fontWeight: 'bold'}
});
// Add the legendPanel to the map.
var legendPanel = ui.Panel([legendTitle, colorBar, legendLabels]);
Map.add(legendPanel);
Map.centerObject(c,5.5);
Map.setOptions('SATELLITE');