I want to get sum array of list

Question

String getTotalPayment({ List<List<double?>>? totalPrice}) {
totalPrice = [[132], [143], [110]];
if (totalPrice.isEmpty) {
  return "0";
} else {
  double sum = 0;
  for (var i = 0; i < totalPrice.length; i++) {
    sum += totalPrice[i] as double;
  }
  // totalPrice.reduce((value, current) => value + current);
  return sum.toString();
}


 }

I get this error:

type 'List<double?>' is not a subtype of type 'double' in type cast!!

uTotalPayment: pending.data !=null ?
                        getTotalPayment(totalPrice: pending.data!.map((e) => e.invoices!.map((e) => e.total!.toDouble()).toList()

Help me! thanks in advanced – Chhily Lim Jul 20 '22 at 02:35 — Chhily Lim, Jul 20 '22 at 02:35
have you tried to loop again since its inside in the list? – Arbiter Chil Jul 20 '22 at 03:08 — Arbiter Chil, Jul 20 '22 at 03:08

Arbiter Chil · Accepted Answer · 2022-07-20T03:16:27.187

2

Try to loop it again to get the data inside on each data on the list

  List<List<double?>> totalPrice = [[132], [143], [110]];
  double sum = 0;
  for(var x in totalPrice){
      for(var y in x){
          sum += y!;
      }
  }
  print(sum.toString()); // Result 385

you can also use fold answered by @Kaushik Chandru

edited Jul 20 '22 at 03:16

answered Jul 20 '22 at 03:11

Arbiter Chil

1,061
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yes sir!! it's work totally easier than anything i have tried! thanks so much! – Chhily Lim Jul 20 '22 at 04:43
This answer so easy to read but It will crash if there is a null value. – Wilson Tran Jul 20 '22 at 07:33

score 1 · Answer 2 · answered Jul 20 '22 at 02:58

1

Since you have a list of list. You may have to use a nested loop to get the sum. You can give this a try

double sum = totalPrice.fold(0, (a,b) => (a.fold(0, (c,d) => c+d)) + (b.fold(0, (e,f)=>e+f)));
print(sum);

answered Jul 20 '22 at 02:58

Kaushik Chandru

15,510
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Wilson Tran · Answer 3 · 2022-07-20T07:10:07.807

1

Use standard collection functions:

final sum = items
  .expand((element) => element) // Flattern list
  .whereType<double>() // Remove null elements
  .fold<double>(0.0, (previousValue, element) => previousValue + element); // Sum of

edited Jul 20 '22 at 07:10

answered Jul 20 '22 at 06:55

Wilson Tran

4,050
3
22
31

I have tried this too, but a bit complex to understand – Chhily Lim Jul 20 '22 at 07:10
@ChhilyLim This is a common approach in modern programming languages. In my answer, I have referenced from https://stackoverflow.com/questions/15413248/how-to-flatten-a-list and https://stackoverflow.com/questions/10405348/what-is-the-cleanest-way-to-get-the-sum-of-numbers-in-a-collection-list-in-dart – Wilson Tran Jul 20 '22 at 07:25

score -2 · Answer 4 · answered Jul 20 '22 at 03:36

try this

String getTotalPayment({ List<List<double?>>? totalPrice}) {
totalPrice = [[132], [143], [110]];
if (totalPrice.isEmpty) {
  return "0";
} else {
  double sum = 0;
  for(var x in totalPrice){
      for(var y in x){
          sum += y!;
      }
  }
  // totalPrice.reduce((value, current) => value + current);
  return sum.toString();
}

I want to get sum array of list

4 Answers4