04 Calculate Heatwave

var image2041 = ee.Image("projects/heatwave0214/assets/TM_SSP245_HWF/Interpolation_TM_SSP245_HWF_2041") 

var geometry =ee.FeatureCollection("projects/heatwave0214/assets/basicpolygon/Chinaregion_NOTW")
// .filter(ee.Filter.eq('zone', 'Central China'))
.geometry();
 
var InnerJoin  = require('users/geogismx/mountain_solar:join.js'); 
 
var i;
for (i = 2041; i < 2042; i++) {
 
  function InnerJoin(primary, secondary, filter, join) {
      join = typeof join !== 'undefined' ?  join : ee.Join.inner();
      var JoinedImgCol_raw = join.apply(primary, secondary, filter);
      var joinedImgCol = JoinedImgCol_raw.map(joinfea);
      return ee.ImageCollection(joinedImgCol);
  } 
  
 
  
  function functocol(year){
      // Original string 
      var str = 'projects/heatwave0214/assets/CN_GDDP_EHF_SSP245_TM/Interpolation_EHF_ssp245_TM_10km_';
      // Joining the strings together
      var stryear   = year.toString();
      var asset = str.concat(stryear); //image name string
      var img = ee.Image(asset); 
      // print("img",img)
      var meantemp = multibandstoImageCollection(img);
      var newcoll = meantemp.map(function(image){
      var start = stryear.concat('-05-01');
      start = ee.Date(start);
      var dateindex = image.get('system:index');
      //var dateofimage = dateList(dateindex);
      var index = ee.Number.parse(dateindex);
      //var len = parseInt(index);
      var date = start.advance(index,'day');
      var month = date.get('month');
      //var date = ee.Date(daily_coll.get(len));
      return ee.Image(image).setMulti({
              'system:time_start' : date,
              'system:time_end'   : date,
              'month'             : month
      });
      });
      return newcoll;
  }
  
  function multibandstoImageCollection(image) {
    function selectBand(image) {
      return function(bandName) {
        return image.select([bandName]).rename('EHF');
      }
    }
    var bandNames = image.bandNames()
    return ee.ImageCollection.fromImages(bandNames.map(selectBand(image)))
  }
  
  function heatwave(imgcoll,maxThresh){
  
    var dataset = imgcoll.map(function(img){
         return img.addBands(ee.Image.constant(0).toDouble().rename('counter'));
      }).sort('system:time_start');
    
    function heatSpells(img, list){
      var prev = ee.Image(ee.List(list).get(-1));
      var hot = img.select([0]).gt(maxThresh);
      var accum = prev.select('counter').add(hot).rename('counter');
      var out = img.select([0]).addBands(img.select('counter').where(hot.eq(1),accum));
      return ee.List(list).add(out);
    }
    
    // create first image for iteration
    var first = ee.List([ee.Image(dataset.first())]);
    // apply dry speall iteration function
    var lists = dataset.iterate(heatSpells,first); // get the max value
    lists = ee.List(lists).slice(1,null);
    return ee.ImageCollection.fromImages(lists);
    
  
  }
  
  // HWN mean how many discrete heatwave events for the selected season.
  // HWM means the sum of EHF on all days classed as heatwave days, divide by the number of such days.
  // HWA refers to the hottest day of the hottest heatwave of the year. 
  // The hottest heatwave is the one with the highest average EHF across all days of the heatwave
  // The hottest day of this heatwave is also selected, based on the day within the heatwave with the highest EHF.
  // HWF the number of days in the sum of the duration of all four events.
  // HWF is the sum of days that belong to a period of at least 3 consecutive days where EHF is positive
  
  function itt1(img, list){
      // get last image
      var prev = ee.Image(ee.List(list).get(-1));
      // find areas gt 1 threshold (gt==1, lt==0)
      var hot =  prev.select('subwave1').eq(1);
      // add previous day counter to today's counter
      var accum = img.select('subwave1').add(hot).rename('xcounter');
      // create a result image for iteration
      var out = img.addBands(accum);
      return ee.List(list).add(out);
  }
  
  
  function itt2(img, list){
      // get last image
      var prev = ee.Image(ee.List(list).get(-1));
      // find areas eq 1 and eq 0
      var hot =  img.select('xcounter').eq(0).and(prev.select('xcounter').eq(1));
      // add previous day counter to today's counter
      var accum = img.select('xcounter').add(hot).rename('xcounter1');
      // create a result image for iteration
      var out = img.addBands(accum);
      return ee.List(list).add(out);
  }
  
  function itt3(img, list){
      // get last image
      var prev = ee.Image(ee.List(list).get(-1));
      // find areas eq 1 and eq 0
      var hot =  img.select('heat_identity').eq(1).and(prev.select('heat_identity').eq(0));
      // add previous day counter to today's counter
      var accum = img.select('newcounter').add(hot).rename('accumpoint');
      // create a result image for iteration
      var out = img.addBands(accum);
      return ee.List(list).add(out);
  }
  
  function itt4(img, list){
      var prev = ee.Image(ee.List(list).get(-1));
      var hot  = img.select('counter').gt(0);
      //var accumEHF = prev.select('mEHF').multiply(hot).add(img.select('mEHF')).rename('accumEHF')
      //var accumEHF = part1;
      //var prevs = prev.select('mEHF').rename('accumEHF')
      img = img.select('accumEHF').where(hot.eq(1),prev.select('accumEHF').add(img.select('accumEHF')))
      //var accum = img.select('mEHF').multiply(hot);
      //var accum = prev.select('mEHF').multiply(hot).add(img.select('mEHF')).rename('tEHF');
      var out = img;
      //var accumEHF = img.select('tEHF').where(hot.eq(1),accum);
      //var out = img.addBands(accumEHF.toDouble());
      return ee.List(list).add(out);
    }
  
  //print(HWFcol)
  // create first image for iteration
  
  function silotemp(year){
    var stryear = year.toString();
    var start = stryear.concat('-05-01');
    start = ee.Date(start);
    var end   = start.advance(5,'month');
    var yearofsilo = ee.ImageCollection(silo).filterDate(start,end);
    //print(yearofsilo)
    var newsilo    = yearofsilo.map(function(image){
      var maxtemp  = image.select('max_temp');
      var mintemp  = image.select('min_temp');
      var meantemp = maxtemp.add(mintemp).divide(2);
      meantemp = meantemp.rename('Tmean');
      //#############################//
      //Before 2017, 'date' property name is 'Date'
      //After  2017, 'date' property name is 'date'
      //#############################//
      var date =  image.get('system:time_start');
      date = ee.Date(date);
      var month = date.get('month');
      return meantemp.setMulti({
              'system:time_start' :date,
              'system:time_end'   :date,
              'month'             :month
      });
    });
    return newsilo;
  }
  
  
  
  
  // var i = 2018;
  
  //var tempcol = silotemp(i); 
  
  var EHF_Dataset = functocol(i);
  
  // print("EHF_Dataset",EHF_Dataset)
  
  var HWFdataset = heatwave(EHF_Dataset,0).map(function(img){
         return img.addBands(ee.Image.constant(0).toDouble().rename('newcounter'));
      }).sort('system:time_start');

//创建一个名为 "HWFcol" 的图像集合中包含 "subwave1" 和 "subwave2" 这两个波段
//它们分别表示短暂的热浪和较长时间的热浪
  
  var HWFcol = HWFdataset.map(function(img){
      var newcounter = img.select('newcounter');
      var subcount1 = newcounter.where(img.select('counter').eq(3),1);
      var subcount2 = newcounter.where(img.select('counter').gt(3),1);
      return img.addBands(subcount1.rename('subwave1')).addBands(subcount2.rename('subwave2'));
  });
  
  
  var first1   = ee.List([ee.Image(HWFcol.first())]);
  // reverse the  imglist
  var n = HWFcol.size();
  
  var HWFcols = ee.List(HWFcol.toList(n)).reverse();
  // make it into imgcoll
  HWFcols     = ee.ImageCollection.fromImages(HWFcols);
  var list1   = HWFcols.iterate(itt1,first1);
  list1       = ee.List(list1).slice(1,null);
  var HWFcoln = ee.ImageCollection.fromImages(list1);
  
  // print(HWFcoln);
  
  HWFcoln = HWFcoln.select([0,1,2,4,5])
    
  var first2 = ee.List([ee.Image(HWFcoln.first())]);
  var list2 = HWFcoln.iterate(itt2,first2);
  list2 = ee.List(list2).slice(1,null).reverse();
  var HWFcolns = ee.ImageCollection.fromImages(list2);
  
  //print(HWFcolns)
  HWFcolns = HWFcolns.map(function(img){
      var EHF       = img.select('EHF');
      var subwave2  = img.select('subwave2');
      var xcounter1 = img.select('xcounter1');
      var nheat     = subwave2.add(xcounter1);
      var mEHF      = nheat.multiply(EHF);
      var accumEHF      = mEHF;
      return img.addBands(nheat.rename('heat_identity')).addBands(mEHF.rename('mEHF')).addBands(accumEHF.rename('accumEHF'));
  });
  
  //print(HWFcolns)
  HWFcolns = HWFcolns.select([0,1,2,6,7,8])
  
  var first3 = ee.List([ee.Image(HWFcolns.first())]);
  
  
  HWFcolns = ee.List(HWFcolns.toList(n)).reverse();
  HWFcolns     = ee.ImageCollection.fromImages(HWFcolns);
  var list3 = HWFcolns.iterate(itt3,first3);
  list3 = ee.List(list3).slice(1,null).reverse();
  HWFcolns = ee.ImageCollection.fromImages(list3);
  
  //print(HWFcolns)
  
  HWFcolnt = HWFcolns.select([1,6]);
  var first4 = ee.List([ee.Image(HWFcolns.first())]);
  // apply EHF iteration function
  var list4 = HWFcolns.iterate(itt4,first4); // get the max value
  list4 = ee.List(list4).slice(1,null);
  var HWFcolnt = ee.ImageCollection.fromImages(list4);
  
  // print(HWFcolnt);
  
  //
  
  var EHFcollection = InnerJoin.InnerJoin(HWFcolns.select([0,1,3,4,6]), HWFcolnt, InnerJoin.filterTimeEq);
  // print("EHFcollection", EHFcollection)
  
  EHFcollection = EHFcollection.map(function(img){
    
    var accumEHF     = img.select('accumEHF').multiply(img.select('accumpoint')).rename('accumEHF');
    var accumcounter = img.select('counter').multiply(img.select('accumpoint')).rename('maxlens');
    var meanEHF      = accumEHF.divide(accumcounter);
    var mEHF         = img.select('mEHF');
    return mEHF.addBands(meanEHF.rename('meanEHF')).addBands(img.select('accumpoint')).addBands(accumcounter).addBands(accumEHF).copyProperties(img,img.propertyNames());
    
  });
  
  var HWD     = EHFcollection.select('maxlens').reduce(ee.Reducer.max());
  
  HWD = HWD.rename("HWD");
  
  var HWA     = EHFcollection.select('mEHF').reduce(ee.Reducer.max());
  
  HWA = HWA.rename("HWA");
  
  var HWF     = EHFcollection.select('maxlens').reduce(ee.Reducer.sum());
  
  HWF = HWF.rename("HWF");
  
  var HWA_Sum = EHFcollection.select('meanEHF').reduce(ee.Reducer.sum());
  
  var HWN     = EHFcollection.select('accumpoint').reduce(ee.Reducer.sum());
  
  HWN = HWN.rename("HWN");
  
  var HWM   = HWA_Sum.divide(HWN);
  
  HWM = HWM.rename("HWM");
  
  // var HWF = HWFcolf.select('subwave1').reduce(ee.Reducer.sum());
  // Map.addLayer(HWF.clip(geometry),{min:0,max:150,palette:'#9ecae1,#ffffff,#ffeda0,#feb24c,#f03b20'},'Total heatwave days');
  // print("HWF",HWF)
  
  // Map.addLayer(image2041,{min:0,max:150,palette:'#9ecae1,#ffffff,#ffeda0,#feb24c,#f03b20'},'image2041');
  // print("image2041",image2041)
  
  var task = 'Interpolation_TM_SSP245_HWF_'+i.toString()
  var folder = 'projects/heatwave0214/assets/TM_SSP245_HWF'
  Export.image.toAsset({
    image: HWF,
    description: task,
    assetId:folder.concat('/').concat(task),
    region:geometry.bounds(),
    scale: 11132,
    crs:  'EPSG:4326'
  })
}