我正在使用R
的combn
函数获取变量y
的每个值组合,并每次取2个值,然后根据变量x
进行分组。 我期望的最终结果是表格c
。
但是当我尝试在tidyverse
中实现它时出现了一些(非常)错误的情况。
library(tidyverse)
df <- tibble(x = c(1, 1, 1, 2, 2, 2, 2),
y = c(8, 9, 7, 3, 5, 2, 1))
# This is what I want
a <- combn(df$y[df$x == 1], 2)
a <- rbind(a, rep(1, ncol(a)))
b <- combn(df$y[df$x == 2], 2)
b <- rbind(b, rep(2, ncol(b)))
c <- cbind(a, b)
c <- tibble(c)
c <- t(c)
# but using tidyverse it does not work
df %>% group_by(x) %>% mutate(z = combn(y, 2))
#> Error: Problem with `mutate()` input `z`.
#> x Input `z` can't be recycled to size 3.
#> i Input `z` is `combn(y, 2)`.
#> i Input `z` must be size 3 or 1, not 2.
#> i The error occurred in group 1: x = 1.
Created on 2020-11-18 by the reprex package (v0.3.0)