为非零值的运行创建组ID [英] Create group ID for runs of non-zero values

问题描述

我想在向量中找到连续的非零元素(由至少一个零分隔)，并为每个组分配一个ID(随后的整数).

I would like to find contiguous runs of non-zero elements in a vector (separated by at least one zero), and to assign an ID to each group (subsequent integer).

玩具向量:

value <- c(1, 1, 2, 3, 4, 3, 0, 0, 0, 1, 2, 3, 9, 8, 0, 0, 3, 2)

在此示例中，存在三个非零值的游程:[1,1,2,3,4,3]，[1,2,3,9,8]，[3,2]，分开按一个或多个零的块.

In this example, there are three runs of non-zero values: [1,1,2,3,4,3], [1,2,3,9,8], [3,2], separated by chunks of one or more zeros.

每个非零运行应具有唯一的ID:1、2、3 ...零运行应具有NA作为ID:

Each non-zero run should have a unique ID: 1, 2, 3... Runs of zero should have NA as ID:

   value id
1      1  1
2      1  1
3      2  1
4      3  1
5      4  1
6      3  1
7      0 NA
8      0 NA
9      0 NA
10     1  2
11     2  2
12     3  2
13     9  2
14     8  2
15     0 NA
16     0 NA
17     3  3
18     2  3

推荐答案

使用rle().首先创建一个新的向量，用NA替换零.

Using rle(). First create a new vector replacing the zeros with NA.

x <- match(value != 0, TRUE)
with(rle(!is.na(x)), {
    lv <- lengths[values]
    replace(x, !is.na(x), rep(seq_along(lv), lv))
})
# [1]  1  1  1  1  1  1 NA NA NA  2  2  2  2  2 NA NA  3  3

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