Question 78016 in Flutter Question posted in
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how is the logic of neighbor values in to sub lists from integer list – Flutter

input =>

List integerList =[1,2,3,4,30,31,50,51,100];

expecting output =>

List subLists =[[1,2,3,4],[30,31],[50,51],[100]];

basic criteria, subtraction result of each in between values of subgroups should be less than 10

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2

Answers


  1. 0

    OLD ANSWER

    Here’s an example (assuming grouping by number length):

    import 'package:collection/collection.dart';

void main() {
  List integerList =[1,2,3,4,50,51,100];
  final result = integerList
      .groupListsBy((element) => element.toString().length)
      .values
      .toList();

  print(result); // prints: [[1, 2, 3, 4], [50, 51], [100]]
}

    EDIT:

    NEW ANSWER

    I believe this could do what you like:

      List integerList = [1,2,3,4,8,30,31,50,51,100];
  final result = integerList.fold<List<List<int>>>(
      [[]],
      (previousValue, element) => previousValue.last.isEmpty ||
              (previousValue.last.last - element).abs() < 10
          ? [
              ...previousValue.take(previousValue.length - 1),
              [...previousValue.last, element]
            ]
          : [
              ...previousValue,
              [element]
            ]);

  print(result); // [[1, 2, 3, 4, 8], [30, 31], [50, 51], [100]]
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  2. 0

    This function return what you want:

    List getGroupedList(List<int> integerList) {
    List<List<int>> groupedList = [];
    while (integerList.isNotEmpty) {
      groupedList.add([integerList.first]);
      integerList.removeAt(0);
      while (integerList.isNotEmpty&&integerList.first - groupedList.last.last == 1) {///YOU CAN ALTER THIS 1 TO ANY NUMBER ACCORDING TO YOUR CRITERIA OF DIFFERENCE BETWEEN NUMBERS
        groupedList.last.add(integerList[0]);
        integerList.removeAt(0);
      }
    }
    return groupedList;
  }
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