使用整齐的评估语义将一个字符向量分组为group_by [英] group_by by a vector of characters using tidy evaluation semantics

问题描述

我曾经使用group_by_

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

，但现在不推荐使用group_by_.我不知道如何使用整洁的评估框架.

but now group_by_ is deprecated. I don't know how to do it using the tidy evaluation framework.

推荐答案

有group_by的group_by_at变体:

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:

Above it's simplified version of generalized:

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

在vars内部，您可以使用任何dplyr方式选择变量:

inside vars you could use any dplyr way of select variables:

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))

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