EVItrends

var urban = ee.FeatureCollection("users/continental/GRL_urban5643")
//print("urban",urban)

var citylist = urban.aggregate_array('ORIG_FID')
//print("citylist",citylist)


// EVIdata
var bitwiseExtract = function(input, fromBit, toBit){
      var maskSize = ee.Number(1).add(toBit).subtract(fromBit)
      var mask = ee.Number(1).leftShift(maskSize).subtract(1)
      return input.rightShift(fromBit).bitwiseAnd(mask)
}

var qualityControl = function(image){
      var lstErrorMask = bitwiseExtract(image.select('DetailedQA'), 0, 1).eq(0)
      return image.select('EVI').updateMask(lstErrorMask)  
}

// convert the unit of EVI
var convertUnit_EVI = function(image){
  return image.multiply(0.0001).copyProperties(image,['system:time_start','system:time_end'])
}


// masking pixels identified as water and so on
var igbpLandCover = ee.Image('MODIS/061/MCD12Q1/2020_01_01').select('LC_Type1')
var urban_LandCover = igbpLandCover.updateMask(igbpLandCover.neq(11).and(igbpLandCover.neq(15)).and(igbpLandCover.neq(17)))
var maskIGBP = function(image){
  return image.updateMask(urban_LandCover)
}

var year_list = ee.List.sequence(2003,2022)
var season_list = ee.List.sequence(3,12,3)


var bandname = year_list.map(function(year){
  return ee.String(year).slice(0,4)
})
//print("bandname",bandname)

var outputSelectors = ee.List(['ORIG_FID']).cat(bandname).getInfo()
//print("outputSelectors",outputSelectors)

var EVIVis = {
  min: 0.1, 
  max: 0.5, 
  palette: ['040274', '0602ff', '3be285', 'fff705', 'ff0000', '911003'
  ]
}

var EVI = ee.ImageCollection("MODIS/061/MOD13A2")
            .select('EVI')
            .map(maskIGBP)
            //.map(qualityControl)
            .map(convertUnit_EVI)
//print("EVI",EVI)


// first seasonal mean EVI, then yearly mean EVI
var yearly_EVI_JunetoAugust = ee.ImageCollection.fromImages(year_list.map(function(year){
      year = ee.Number(year)
      return EVI.filterDate(ee.Date.fromYMD(year,6,1),ee.Date.fromYMD(year,9,1)).mean()
                .set('system:time_start',ee.Date.fromYMD(year,1,1).millis())
      })).toBands().rename(bandname)
print("yearly_EVI_JunetoAugust",yearly_EVI_JunetoAugust)


var yearly_EVI_DecembertoFebrary = ee.ImageCollection.fromImages(year_list.map(function(year){
      year = ee.Number(year)
      return EVI.filterDate(ee.Date.fromYMD(year,12,1),ee.Date.fromYMD(year.add(1),3,1)).mean()
                .set('system:time_start',ee.Date.fromYMD(year,1,1).millis())
      })).toBands().rename(bandname)
print("yearly_EVI_DecembertoFebrary",yearly_EVI_DecembertoFebrary)

var NH = ee.Image.pixelLonLat().select("latitude").gte(0)
var SH = ee.Image.pixelLonLat().select("latitude").lt(0)

var yearly_EVIsummer_NH = yearly_EVI_JunetoAugust.updateMask(NH)
var yearly_EVIsummer_SH = yearly_EVI_DecembertoFebrary.updateMask(SH)

var yearly_EVI = ee.ImageCollection([yearly_EVIsummer_NH,yearly_EVIsummer_SH]).mosaic()
print("yearly_EVI",yearly_EVI)



for(var j=0;j<5643;j+=30){   
    
    var ID_group = citylist.slice(j,j+30)
    //print(ID_group)
    
    var final_fc = ee.FeatureCollection(ID_group.map(function(city_i){

          var urban_i = urban.filter(ee.Filter.eq('ORIG_FID', city_i)).first()
          
          var yearly_EVIurban = yearly_EVI.reduceRegion(ee.Reducer.mean(),ee.Feature(urban_i).geometry(),1000,null,null,false,10e12,4)

          return ee.Feature(null,yearly_EVIurban).set('ORIG_FID',city_i)
                                  
}))
    print("final_fc",final_fc)
    
    Export.table.toDrive({
            collection: final_fc,
            folder:"core_EVI_yearly_summer",
            description: 'core_EVI_yearly_summer_'+j,
            selectors: outputSelectors,
            fileFormat: 'CSV'
    })
}