Array map

by Dong Nguyen

JavaScript

var a = [[1, 0.3], [1, 0.5], [2, 0.6], [2, 0.7], [3, 0.8], [3, 0.9]];

function merge(arr){
  var tmp = [];
  arr.map(function(item){
    var key = item[0], value = item[1];
    if(!tmp[key]){
      tmp[key] = [value];
    }
    else{
      tmp[key].push(value);
    }
  });

  return tmp.filter(function(item){
    return item ? true : false;
  });
}

var b = merge(a);
console.log(b);