Sort a list based on another list in Dart-CodePudding

I need to sort unsortedList based on the sorting of sortedList.

Example:

List<String> sortedList = ["x", "a", "c", "d", "w"];

// [unsortedList] items need to be also in [sortedList] and in the
// same range (eg. between 0 and 2 position)
List<String> unsortedList = ["a", "x", "c"];

CodePudding user response：

You want the elements of sortedList which also appear in unsortedList, in their original order.

That's not about sorting.

No sorting is needed:

var result = sortedList.where({...unsortedList}.contains).toList();

(You can use unsortedList.contains directly, instead of creating a set, and it's probably even faster for small unsortedLists.)

Or, if your requirement is correct, and the n elements of unsortedList are the first n elements of sortedList in a different order, then maybe just var result = sortedList.sublist(0, unsortedList.length);.

If you actually care about getting the element from unsortedList, not the equal element from sortedList (which may matter if the elements are equal, but not identical), you can do:

var result = sortedList.map({...unsortedList}.lookup).whereNotNull().toList();

where whereNotNull is from package:collection.

CodePudding user response：

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