csv2flare.json

var csv = `MW,A,50
W,B,100
MW,B,100
E,C,70
E,A,90
W,D,200
W,F,190`

var csvArr = csv.split('\n')

csvArr.forEach((item, index, arr) => arr[index] = item.split(','));


var flare = {};

csvArr.forEach((item, index, arr) => {
  if (item[0] in flare) flare[item[0]][item[1]] = item[2];
  else {
    flare[item[0]] = {};
    flare[item[0]][item[1]] = item[2];
  }
})

var flarejson = {name:"flare", children:[]}

for (var key in flare){
  let child = [];
  for (var key2 in flare[key]){
    child.push({name:key2, size:flare[key][key2]});
  }
  flarejson.children.push({name:key, children:child});
}