Need a map of a map in Dart.lang - dart

Question

Learning Dart.lang . Have a php background. Given this code at this link...
Link to full working php algorithm
or to copy the main part here, this is what i got in PHP and works fine. I need to know how to do it in dart:
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}.");
});
}