在我自己的功能中使用summarys和group_by_ [英] Usage summarise_ and group_by_ in my own function

问题描述

我想创建一个简单的函数，它将使用 summaryize _ 和 group_by _ 函数。我知道非标准评估有问题，但我可以解决它。

I'd like to create a simple function which will use summarise_ and group_by_ function. I know that there is a problem with non-standard evaluation but I could fix it.

library(dplyr)
test_function <- function(.data, ..., variable){
  dots <- quote(mean(substitute(variable)))
    group_by_(.data,.dots = lazyeval::lazy_dots(...)) %>% 
    summarise_(.dots = dots)
}

但是当我尝试这样做：

test_function(ggplot2::diamonds, cut, clarity, variable = price)

它不工作。

谢谢

推荐答案

您的问题是您的 quote（）。报价是转义 substitute（），所以它不是以你想要的方式运行。如果您使用 bquote（），则可以使用替换代码，并将结果插入表达式以获取所需内容

Your problem is your quote(). The quote is escaping the substitute() so it's not running the way you want it to. If you use bquote() instead, you can evaulate the substitute and insert the result into the expression to get what you want

test_function <- function(.data, ..., variable){
    dots <- bquote(mean(.(substitute(variable))))
    group_by_(.data,.dots = lazyeval::lazy_dots(...)) %>% 
    summarise_(.dots = dots)
}

test_function(diamonds, cut, clarity, variable = price)
# Source: local data frame [40 x 3]
# Groups: cut
# 
#     cut clarity mean(price)
# 1  Fair      I1    3703.533
# 2  Fair     SI2    5173.916
# 3  Fair     SI1    4208.279
# 4  Fair     VS2    4174.724
# 5  Fair     VS1    4165.141

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