使用Javascript将连续元素分组在一起 [英] Grouping consecutive elements together using Javascript

问题描述

我有一个像这样的元素数组:

I have an array of elements like so:

messages[i]，其中messages[i]仅对i的某些值存在.例如，messages[0]和messages[2]可能存在，但messages[1]不存在.

messages[i], where messages[i] may only exist for certain values of i. For instance messages[0] and messages[2] may exist but not messages[1].

现在，我想将具有连续索引的元素组合在一起，例如，如果存在消息的索引是:

Now I would like to group together elements with continuous indices, for example if the indices for which messages existed were:

2, 3, 4, 5, 8, 9, 12, 13, 14, 15, 16, 17, 20

我想像这样对它们进行分组:

I would like to group them like so:

2, 3, 4, 5

8, 9

12, 13, 14, 15, 16, 17

20

使用Java脚本执行此操作的有效方法是什么?

What would be an effective way to do so using Javascript?

for (i = 0; i < messages.length; i++) {
   if (messages[i].from_user_id == current_user_id) {
   // group the continuous messages together
      } else {
  //group these continuous messages together
   }
}

推荐答案

您可以使用必须递增的计数器变量，并且索引和连续元素之间的差异相同，将它们分组在一个临时数组中.如果两个连续的数组元素的差异有所不同，则必须将临时元素移到result，并且必须为该临时数组分配一个新的数组对象.

You can use a counter variable which has to be incremented and the difference between the index and the consecutive elements are the same, group them in a temporary array. If the difference is varies for two consecutive array elements, the temporary element has to be moved to the result and the temporary array has to be assigned a new array object.

var array = [2, 3, 4, 5, 8, 9, 12, 13, 14, 15, 16, 17, 20];

var result = [], temp = [], difference;
for (var i = 0; i < array.length; i += 1) {
    if (difference !== (array[i] - i)) {
        if (difference !== undefined) {
            result.push(temp);
            temp = [];
        }
        difference = array[i] - i;
    }
    temp.push(array[i]);
}

if (temp.length) {
    result.push(temp);
}

console.log(result);
# [ [ 2, 3, 4, 5 ], [ 8, 9 ], [ 12, 13, 14, 15, 16, 17 ], [ 20 ] ]

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