CODEWITHSUNDEEP
collectionsflutterdart
Magnus
Magnus

Reputation: 18758

How to create a matrix in Dart?

I have a List<String> and I want to create a square matrix (2-dimensional array/list) of Set<String> with the same dimensions as the length of the List<String>.

I tried using 

List.filled(entries.length, List.filled(entries.length, Set<String>()));

but the problem is that it seems that each row of my matrix refers to the same list instance, so changing a value in one row changes it in all the others as well.

So then I tried 

List.filled(entries.length, List.from(List.filled(entries.length, Set<String>())));

but I still have the same problem. Eventually I surrendered and resorted to 

List<List<Set<String>>> matrix = [];

for(int i=0; i<entries.length; i++) {
    List<Set<String>> row = [];
    for (int n = 0; n<entries.length; n++) {
        row.add(Set<String>());
    }
    matrix.add(row);
}

It works, but it's ugly. Is there a cleaner way to do this?

Upvotes: 2

Views: 2394

Answers (2)

Makdir
Makdir

Reputation: 490

Probably, you could use Matrix2 class (or matrixes with other dimensions: Matrix3, Matrix4). Unfortunately, I have no experience in using these classes, but maybe it has a sense for you. These classes have constructors for generating matrix from lists.

Upvotes: 0

Alexandre Ardhuin
Alexandre Ardhuin

Reputation: 76243

List.generate(n, (_) => List.generate(n, (_) => <String>{}));

Upvotes: 5

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