00073_img_expression

/*
Tutorial Code by Amirhossein Ahrari
YouTube: https://www.youtube.com/@amirhosseinahrarigee

This code is part of a tutorial series on Earth Engine programming techniques
presented on the Amirhossein Ahrari YouTube channel. You are free to use and modify
this code for academic and non-academic purposes. Don't forget to subscribe to
the Amirhossein Ahrari channel and follow the videos to support the instructor!
*/

var cor = [
  [24.601591838871006,60.127836641299616], 
  [25.150908245121006,60.127836641299616],
  [25.150908245121006,60.331035392660304],
  [24.601591838871006,60.331035392660304],
  [24.601591838871006,60.127836641299616]
  ]

var geometry = ee.Geometry.Polygon(cor)

var sen2 = ee.ImageCollection("COPERNICUS/S2_SR_HARMONIZED")
.filterBounds(geometry)
.filterDate('2023-07-01','2024-09-01')
.filter(ee.Filter.lt('CLOUDY_PIXEL_OVER_LAND_PERCENTAGE', 10))
.map(function(img){
  var bands = img.select('B.*').multiply(0.0001)
  // ndvi = (nir - red)/(nir + red)
  var ndvi1 = bands.expression('(nir - red)/(nir + red)',{'nir': bands.select('B8'), 'red': bands.select('B4')}).rename('ndvi1')
  var ndvi2 = (bands.select('B8').subtract(bands.select('B4'))).divide(bands.select('B8').add(bands.select('B4'))).rename('ndvi2')
  var ndvi3 = bands.normalizedDifference(['B8','B4']).rename('ndvi3')
  return ee.Image.cat([ndvi1, ndvi2, ndvi3])
  .copyProperties(img, img.propertyNames())
  
  })


var sen2_img = ee.Image('COPERNICUS/S2_SR_HARMONIZED/20230914T095031_20230914T095325_T34VFN')

var sen2_bands = sen2_img.select('B.*').expression('img * 0.0001',{'img': sen2_img.select('B.*')})

var sen2_ndvi = sen2_bands.normalizedDifference(['B8','B4']).rename('ndvi')

Map.addLayer(sen2_ndvi, [], 'ndvi', false)