r - group_by 通过使用整齐评估语义的字符向量

Question

我曾经这样做，使用group_by_

library(dplyr)
group_by <- c('cyl', 'vs')
mtcars %>% group_by_(.dots = group_by) %>% summarise(gear = mean(gear))

但现在group_by_已弃用。我不知道如何使用整洁的评估框架来做到这一点。

Answer 1

将字符向量转换成符号列表并拼接进去

df %>% group_by(!!! syms(group_by))

Answer 2

有以下group_by_at变体group_by：

library(dplyr)
group_by <- c('cyl', 'vs')
mtcars %>% group_by_at(group_by) %>% summarise(gear = mean(gear))

上面是广义的简化版本：

mtcars %>% group_by_at(vars(one_of(group_by))) %>% summarise(gear = mean(gear))

在里面vars你可以使用任何dplyr方式选择变量：

mtcars %>%
    group_by_at(vars(
        one_of(group_by) # columns from predefined set
        ,starts_with("a") # add ones started with a
        ,-hp # but omit that one
        ,vs # this should be always include
        ,contains("_gr_") # and ones with string _gr_
    )) %>%
    summarise(gear = mean(gear))