CODEWITHSUNDEEP
dictionarydartslice
François Constant
François Constant

Reputation: 5496

Slice a Map in Dartlang

I need to slice a Map. I've got it to work like this:

Map sliceMap(Map map, offset, limit) {
  Map result = new Map();
  if (map.length < limit) {
     limit = map.length;
  }
  map.keys.toList().getRange(offset, limit).forEach((key) {
    result[key] = map[key];
  });
  return result;
}

Is there a more efficient way and/or a built-in way? I couldn't find any in the API (https://api.dartlang.org/stable/1.21.0/dart-core/Map-class.html).

From aelayeb solution:

Map sliceMap(Map map, offset, limit) {
  return new Map.fromIterables(
      map.keys.skip(offset).take(limit - offset),
      map.values.skip(offset).take(limit - offset)
  );
}

Upvotes: 2

Views: 1361

Answers (2)

Alexandre Ardhuin
Alexandre Ardhuin

Reputation: 76303

You can use :

Map sliceMap(Map map, offset, limit) {
  return new Map.fromIterable(map.keys.skip(offset).take(limit),
      value: (k) => map[k]);
}

Upvotes: 2

aelayeb
aelayeb

Reputation: 1258

Here is my approach for what is worth :

new Map.fromIterables(
    map.keys.skip(offset).take(limit),
    map.values.skip(offset).take(limit)
);

With this you don't have to make the limit test.

Upvotes: 4

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