R：为包含相同标签的行分配增量编号 [英] R: assign incremental numbers to rows containing a same label

问题描述

给定数据框 df 如下：

chrom   position    strand  value   label
 chr1      17432         -      0   romeo
 chr1      17433         -      0   romeo
 chr1      17434         -      0   romeo
 chr1      17435         -      0   romeo
 chr1      17409         -      1  juliet
 chr1      17410         -      1  juliet
 chr1      17411         -      1  juliet

我想对从1开始共享相同标签的行进行编号，并将这些数字放在一个新列中。 （我不只是想计算他们，目标是数字）。输出应如下所示：

For each group of labels, I would like to number the lines that share the same label starting from 1 and put those numbers in a new column. (I don't just want to count them, the goal is to number them). The output should look something like this:

chrom   position    strand  value   label  number
 chr1      17432         -      0   romeo       1
 chr1      17433         -      0   romeo       2
 chr1      17434         -      0   romeo       3
 chr1      17435         -      0   romeo       4
 chr1      17409         -      1  juliet       1
 chr1      17410         -      1  juliet       2
 chr1      17411         -      1  juliet       3

是否有一个函数或包执行作业？ p>

Is there a function or package that does the job?

推荐答案

dat <- read.table(header = TRUE, text = "chrom   position    strand  value   label
chr1       17432    -           0   romeo
chr1       17433    -           0   romeo
chr1       17434    -           0   romeo
chr1       17435    -           0   romeo
chr1       17409    -           1   juliet
chr1       17410    -           1   juliet
chr1       17411    -           1   juliet")

#install.packages('dplyr')
library(dplyr)
dat %.%
  group_by(label) %.%
  mutate(number = 1:n())

Source: local data frame [7 x 6]
Groups: label

  chrom position strand value  label number
1  chr1    17432      -     0  romeo      1
2  chr1    17433      -     0  romeo      2
3  chr1    17434      -     0  romeo      3
4  chr1    17435      -     0  romeo      4
5  chr1    17409      -     1 juliet      1
6  chr1    17410      -     1 juliet      2
7  chr1    17411      -     1 juliet      3

我相信在R中有很多其他的可能性。Data.Table是一个（见下面的例子）。不确定为什么我需要添加print（）来显示结果。

I am sure there are many other possibilities in R. Data.Table is one (see example below). Not sure why I needed to add print() to show the result however.

require(data.table)
dt <- data.table(dat)
print(dt[, number := 1:.N, by = label])

   chrom position strand value  label number
1:  chr1    17432      -     0  romeo      1
2:  chr1    17433      -     0  romeo      2
3:  chr1    17434      -     0  romeo      3
4:  chr1    17435      -     0  romeo      4
5:  chr1    17409      -     1 juliet      1
6:  chr1    17410      -     1 juliet      2
7:  chr1    17411      -     1 juliet      3

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