dart - 在 Dart.lang 中需要一张 map 的 map

Question

学习 Dart.lang 。有php背景。在此链接中给出此代码...

Link to full working php algorithm

或将主要部分复制到这里，这是我在 PHP 中得到的并且工作正常。我需要知道如何在 Dart 中做到这一点:

foreach ($floors as $x) { 
    $temp = explode("," , $x);    
    $floor[$temp[0]][$temp[1]] = $temp[2];
}

Answer 1

library map;

void main() {
  var temp = """
  1,201,70
  1,301,71
  3,301,31
  1,401,79
  2,501,2
  1,601,171
  2,801,61
  2,901,100
  5,101,54
  4,203,23
  3,201,112""";

  var values = temp.split('\n');
  var floors = new Map<int, Map<int, double>>();
  values.forEach((f) {
    var v = f.trim().split(',');
    var fk = int.parse(v[0]);
    var rk = int.parse(v[1]);
    var rv = double.parse(v[2]);
    if(floors[fk] == null) {
      floors[fk] = new Map<int,double>();
    }
    floors[fk][rk]=rv;
  });

  floors.forEach((fk, fv) {
    var tempSum = 0;
    var lowest = null;
    for(var rk in fv.keys) {
      var temp = fv[rk];
      tempSum += temp;
      if(lowest == null || (lowest > temp)) {
        lowest = temp;
      }
    }
    print("Floor #${fk} has ${fv.length} rooms. The average temp is ${tempSum / fv.length}. The lowest temp is ${lowest}.");
  });
}