我有一个数据框如下,
dt <- data.frame(id = c("a","b","c","d","e","f","g","h","i","j"),
value = c(1,2,1,2,1,1,1,2,1,2))
> dt
id value
1 a 1
2 b 2
3 c 1
4 d 2
5 e 1
6 f 1
7 g 1
8 h 2
9 i 1
10 j 2
我希望基于列value创建一个列,这样每当它在value列中遇到2时,它就会分配一个新的值组号。输出看起来像,
dtgroup <- data.frame(id = c("a","b","c","d","e","f","g","h","i","j"),
value = c(1,2,1,2,1,1,1,2,1,2),
group = c(1,1,2,2,3,3,3,3,4,4))
> dtgroup
id value group
1 a 1 1
2 b 2 1
3 c 1 2
4 d 2 2
5 e 1 3
6 f 1 3
7 g 1 3
8 h 2 3
9 i 1 4
10 j 2 4
有什么想法吗?谢谢!
最佳答案
我们可以像下面一样使用findInterval
> transform(dt, group = 1 + findInterval(seq_along(value), which(value == 2), left.open = TRUE))
id value group
1 a 1 1
2 b 2 1
3 c 1 2
4 d 2 2
5 e 1 3
6 f 1 3
7 g 1 3
8 h 2 3
9 i 1 4
10 j 2 4
或剪切
> transform(dt, group = as.integer(cut(seq_along(value), c(-Inf, which(value == 2)))))
id value group
1 a 1 1
2 b 2 1
3 c 1 2
4 d 2 2
5 e 1 3
6 f 1 3
7 g 1 3
8 h 2 3
9 i 1 4
10 j 2 4
关于r - 如何根据另一列的模式创建组?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/71410975/