枚举或映射Dart中具有索引和值的列表 [英] Enumerate or map through a list with index and value in Dart

问题描述

在dart中，有任何与普通项等效的东西：

In dart there any equivalent to the common:

enumerate(List) -> Iterator((index, value) => f)
or 
List.enumerate()  -> Iterator((index, value) => f)
or 
List.map() -> Iterator((index, value) => f)

这似乎是最简单的方法，但

It seems that this is the easiest way but it still seems strange that this functionality wouldn't exist.

Iterable<int>.generate(list.length).forEach( (index) => {
  newList.add(list[index], index)
});

编辑：

由于@ hemanth-raj，我得以找到所需的解决方案。
我会把它放在这里给需要做类似事情的人。

Thanks to @hemanth-raj i was able to find the solution I was looking for. I'll put this here for anyone who needs to do something similar.

List<Widget> _buildWidgets(List<Object> list) {
    return list
        .asMap()
        .map((index, value) =>
            MapEntry(index, _buildWidget(index, value)))
        .values
        .toList();
}

或者，您可以创建一个同步生成器函数以返回可迭代的

Alternatively you could create a synchronous generator function to return a iterable

Iterable<MapEntry<int, T>> enumerate<T>(Iterable<T> items) sync* {
  int index = 0;
  for (T item in items) {
    yield MapEntry(index, item);
    index = index + 1;
  }
}

//and use it like this.
var list = enumerate([0,1,3]).map((entry) => Text("index: ${entry.key}, value: ${entry.value}"));

推荐答案

有一个 asMap 方法可将列表转换为映射，其中键是索引，值是索引处的元素。请在此处中查看文档。

There is a asMap method which converts the list to a map where the keys are the index and values are the element at index. Please take a look at the docs here.

示例：

List _sample = ['a','b','c'];
_sample.asMap().forEach((index, value) => f);

希望这会有所帮助！

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