我有一个tibble
,其中列以数字命名(例如1
(。我创建了一个函数来计算列之间的差异,但我不知道如何使用这种类型的列:
<!-- language-all: lang-r -->
library(tidyverse)
df <- tibble(`1` = c(1,2,3), `2` = c(2,4,6))
# This works
df %>%
mutate(diff = `1` - `2`)
#> # A tibble: 3 x 3
#> `1` `2` diff
#> <dbl> <dbl> <dbl>
#> 1 1 2 -1
#> 2 2 4 -2
#> 3 3 6 -3
# But this doesn't
calc_diffs <- function(x, y){
df %>%
mutate(diff := !!x - !!y)
}
calc_diffs(1, 2)
#> # A tibble: 3 x 3
#> `1` `2` diff
#> <dbl> <dbl> <dbl>
#> 1 1 2 -1
#> 2 2 4 -1
#> 3 3 6 -1
<sup>Created on 2020-10-14 by the [reprex package](https://reprex.tidyverse.org) (v0.3.0)</sup>
我们可以转换为符号并评估
calc_diffs <- function(x, y){
df %>%
mutate(diff := !! rlang::sym(x) - !!rlang::sym(y))
}
然后,我们只传递一个字符串作为参数
calc_diffs("1", "2")
# A tibble: 3 x 3
# `1` `2` diff
# <dbl> <dbl> <dbl>
#1 1 2 -1
#2 2 4 -2
#3 3 6 -3
列名是字符串。我们可以传递索引来对列进行子集设置,但这里的列名是一个以数字开头的异常名称。因此,我们可以使用paste
用backreference包装它,或者只传递一个字符串,转换为sym
bol并计算(!!
(
这行吗:
> df <- tibble(`1` = c(1,2,3), `2` = c(2,4,6))
> df
# A tibble: 3 x 2
`1` `2`
<dbl> <dbl>
1 1 2
2 2 4
3 3 6
> calc_diffs <- function(x, y){
+ df %>%
+ mutate(diff = {{x}} - {{y}})
+ }
> calc_diffs(`1`,`2`)
# A tibble: 3 x 3
`1` `2` diff
<dbl> <dbl> <dbl>
1 1 2 -1
2 2 4 -2
3 3 6 -3
>