How to delete duplicates in a dart List? list.distinct()?

Question

How do i delete duplicates from a list without fooling around with a set? Is there something like list.distinct()? or list.unique()?

void main() {
  print(\"         


        

Answer 1

Use toSet and then toList

  var ids = [1, 4, 4, 4, 5, 6, 6];
  var distinctIds = ids.toSet().toList();

Result: [1, 4, 5, 6]

Or with spread operators:

var distinctIds = [...{...ids}];

Answer 2

try the following

List<String> duplicates = ["a","c","a"];

duplicates = duplicates.toSet().toList();

check the Dartpad link - https://dartpad.dev/4d3a724429bbd605f4682b7da253a16e

Answer 3

Set works okay, but it doesn't preserve the order. Here's another way using LinkedHashSet:

import "dart:collection";

void main() {
  List<String> arr = ["a", "a", "b", "c", "b", "d"];
  List<String> result = LinkedHashSet<String>.from(arr).toList();
  print(result); // => ["a", "b", "c", "d"]
}

https://api.dart.dev/stable/2.4.0/dart-collection/LinkedHashSet/LinkedHashSet.from.html

Answer 4

void uniqifyList(List<Dynamic> list) {
  for (int i = 0; i < list.length; i++) {
    Dynamic o = list[i];
    int index;
    // Remove duplicates
    do {
      index = list.indexOf(o, i+1);
      if (index != -1) {
        list.removeRange(index, 1);
      }
    } while (index != -1);
  }
}

void main() {
  List<String> list = ['abc', "abc", 'def'];
  print('$list');
  uniqifyList(list);
  print('$list');
}

Gives output:

[abc, abc, def]
[abc, def]

Answer 5

Using dart 2.3+, you can use the spread operators to do this:

final ids = [1, 4, 4, 4, 5, 6, 6]; 
final distinctIds = [...{...ids}];

Whether this is more or less readable than ids.toSet().toList() I'll let the reader decide :)