将变量传递给 tidyr::pivot_wider 的 names_glue 参数答案

【问题标题】：Passing variables into the names_glue parameter of tidyr::pivot_wider将变量传递给 tidyr::pivot_wider 的 names_glue 参数
【发布时间】：2021-01-14 14:09:14
【问题描述】：

这里有一些愚蠢的数据，我们使用两个名称进行更广泛的透视：

library(tidyr)

df <- data.frame(
    food = c('banana','banana','banana','banana','cheese','cheese','cheese','cheese'),
    binary = c(rep(c('yes','no'), 4)),
    car = c('toyota','subaru','mazda','skoda','toyota','subaru','mazda','skoda'),
    fun = c(2,4,3,6,2,4,2,3))

df %>%
    pivot_wider(
        id_cols = food,
        names_from = c(car, binary),
        values_from = fun)

如果我们想改变新变量名的格式，例如，从toyota_yes 到yes_toyota，我们使用names_glue 参数：

df %>%
    pivot_wider(
        id_cols = food,
        names_from = c(car, binary),
        names_glue = "{binary}_{car}",
        values_from = fun)

我面临的问题是找到将变量名传递给names_glue 参数的正确语法。将变量传递给names_from 很容易，例如：

var1 <- 'car'
var2 <- 'binary'
df %>%
    pivot_wider(
        id_cols = food,
        names_from = c(var1, var2),
        values_from = fun)

但我们不能直接使用names_glue：

df %>%
    pivot_wider(
        id_cols = food,
        names_from = c(var1, var2),
        names_glue = "{var1}_{var2}",
        values_from = fun)

错误：列名 car_binary、car_binary 和 car_binary 不得重复。

大概它正在评估变量并将结果字符串（即'car'或'binary'）传递给glue函数。我玩过一些我通常用于整洁评估的东西（!!sym(...) 等），但没有任何工作。所需的输出如下，使用 names_glue 参数的变量：

# A tibble: 2 x 5
  food   yes_toyota no_subaru yes_mazda no_skoda
  <fct>       <dbl>     <dbl>     <dbl>    <dbl>
1 banana          2         4         3        6
2 cheese          2         4         2        3

Here is the commit that added the names_glue parameter to pivot_wider -- although I can't really figure out how to troubleshoot with this.

【问题讨论】：

标签： r tidyr tidyeval r-glue

【解决方案1】：

你可以使用sprtinf/paste0来构造字符串：

library(tidyr)
df %>%
  pivot_wider(
    id_cols = food,
    names_from = c(var1, var2),
    names_glue = sprintf('{%s}_{%s}', var2, var1),
    values_from = fun)

#  food   yes_toyota no_subaru yes_mazda no_skoda
#  <chr>       <dbl>     <dbl>     <dbl>    <dbl>
#1 banana          2         4         3        6
#2 cheese          2         4         2        3

【讨论】：

【解决方案2】：

我们可以用glue创建模式

library(dplyr)
library(tidyr)
df %>%
     pivot_wider(
         id_cols = food,
         names_from = c(var1, var2),
         names_glue = glue::glue("{[var1]}_{[var2]}", .open = '[', .close = ']'),
         values_from = fun)
# A tibble: 2 x 5
#  food   toyota_yes subaru_no mazda_yes skoda_no
#  <chr>       <dbl>     <dbl>     <dbl>    <dbl>
#1 banana          2         4         3        6
#2 cheese          2         4         2        3

【讨论】：