使用跨与.names突变：“GLUE不能将函数插值到字符串中”错误

Question

我有不同地区候选人的选举结果。来源有每个候选人的票数和每个地区的总票数。我想为每个候选人在每个地区的得票率添加变量。

library(tidyverse)
df <- data.frame(district = 1:3,
                 cand1 = c(12, 2, 14),
                 cand2 = c(2, 6, 23),
                 cand3 = c(3, 16, 2),
                 total = c(17, 24, 39))
df %>% 
  mutate(across(2:4, ~ .x/total*100))
#>   district     cand1    cand2     cand3 total
#> 1        1 70.588235 11.76471 17.647059    17
#> 2        2  8.333333 25.00000 66.666667    24
#> 3        3 35.897436 58.97436  5.128205    39
  
df %>% 
  mutate(across(2:4, ~ .x/total*100, .names = "{.col}_pct"))
#> Error: Problem with `mutate()` input `..1`.
#> x glue cannot interpolate functions into strings.
#> * object '.col' is a function.
#> i Input `..1` is `across(2:4, ~.x/total * 100, .names = "{.col}_pct")`.

我最初认为这是对anthers和.names应该如何工作的误解，但当我使用anthers小插曲中的示例时，我得到了同样的错误。我在本地计算机和RStudio云上都尝试过这一点。DPLYR版本1.0.1。

library(dplyr)

iris %>%
  group_by(Species) %>%
  summarise(across(starts_with("Sepal"), mean, .names = "mean_{.col}"))
#> Error: Problem with `summarise()` input `..1`.
#> x glue cannot interpolate functions into strings.
#> * object '.col' is a function.
#> i Input `..1` is `across(starts_with("Sepal"), mean, .names = "mean_{.col}")`.
#> i The error occurred in group 1: Species = "setosa".

^{由reprex包(v0.3.0)于2020-08-12创建}

Answer 1

根据？跨，它不是.col，只是col

.names-默认值(NULL)相当于“{col}”（用于单个函数的情况）和“{col}_{fn}”（用于.fns使用列表的情况）。

library(dplyr)
df %>% 
   mutate(across(2:4, ~ .x/total*100, .names = "{col}_pct"))
#  district cand1 cand2 cand3 total cand1_pct cand2_pct cand3_pct
#1        1    12     2     3    17 70.588235  11.76471 17.647059
#2        2     2     6    16    24  8.333333  25.00000 66.666667
#3        3    14    23     2    39 35.897436  58.97436  5.128205