CODEWITHSUNDEEP
flutterdart
Salwan Adnan
Salwan Adnan

Reputation: 1

how to sum values of some map keys in dart

I have a map of items and its prices, I want to sum some selected(not all) values of keys how? in dart I have tried all values except one but cant do other than this. my map contains string key and double value

Upvotes: 0

Views: 816

Answers (1)

Tomer Ariel
Tomer Ariel

Reputation: 1545

In general, you want to perform a filter-map-reduce operation here - filter to get all elements which have a certain property, map to extract the value from each element, and finally reduce to aggregate the results to a single value (the sum, in this case).

An example in Dart could look something like this:

  final Map<String, int> map = {
    "item": 10,
    "anotherItem": 20,
    "yetAnotherItem": 30
  };
  final sumOfEvenLengthKeys = map.entries
      .where((e) => e.key.length % 2 == 0)
      .map((e) => e.value)
      .reduce((a, b) => a + b);

Which would produce 40.

Upvotes: 1

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