Scala for循环.简洁地获取索引 [英] Scala for-loop. Getting index in consice way

问题描述

在这段代码中，我想增加index到每个yield ing结果中.

In this code I want to increment index to put it to each yielding result.

var index=0

for(str <- splitToStrings(text) ) yield  {

  if (index != 0) index += 1               // but index is equal to `0` all the time

  new Word(str, UNKNOWN_FORM, index )
}

为什么我不能更改index?那么，为了简洁起见，实现此逻辑的最佳方法是什么?

Why I can not change index ? And what the best way to implement this logic then, trying to be concise?

推荐答案

大多数类似序列的集合中的zipWithIndex方法将为您提供从零开始的索引，并随每个元素递增:

The zipWithIndex method on most sequence-like collections will give you a zero-based index, incrementing with each element:

for ((str, index) <- splitToStrings(text).zipWithIndex)
  yield new Word(str, UNKNOWN_FORM, index)

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