在 dplyr 0.7+ 函数中重命名 [英] Rename in dplyr 0.7+ function

问题描述

我在使用 dplyr 重命名函数中的列时遇到困难.我已经找到了关于非标准评估和 enquo 使用的有用帖子(例如，http://dplyr.tidyverse.org/articles/programming.html 和 在自定义 dplyr 函数中更改结果变量的名称).最终目标是使用函数来汇总每个组，然后将列重命名为比原始变量名称更有意义的名称.

I am having difficulty renaming columns in a function using dplyr. I have already found helpful posts on nonstandard evaluation and the use of enquo (e.g., http://dplyr.tidyverse.org/articles/programming.html and Changing names of resulting variables in custom dplyr function). The ultimate goal is to use the function to summarise each group, and then rename the columns into something more meaningful than the original variable names.

这是一个简单的例子，除了被注释掉的行.

Here is a simple example, which works except for the commented-out lines.

library(tidyverse)

myfunc <- function(df, groupvar, colvar, grouplab, collab) {
  groupvar <- enquo(groupvar)
  colvar <- enquo(colvar)
  grouplab <- enquo(grouplab)  # quo_name instead?
  collab <- enquo(collab)  # quo_name instead?

t <- df %>%
  select(!!groupvar, !!colvar) %>%
  group_by(!!groupvar, !!colvar) %>%
  summarise(
    Frequencies = length(!!colvar),
    Percentages = length(!!colvar) / nrow(df)
    ) %>%
  mutate(
    Frequencies = scales::comma(Frequencies),
    Percentages = scales::percent(Percentages)
    ) #%>%
# rename(
#    (!!grouplab) = !!groupvar,  # add a more descriptive grouping var label
#    (!!collab) = !!colvar)  # add a more descriptive column var label

# Error: unexpected '=' in: rename((!!grouplab) = "

...  # code to create an xtable, print it into LaTeX
}

myfunc <- (df = mtcars, groupvar = gear, colvar = cyl, grouplab = "Vehicle Gears", collab = "Vehicle Cylinders")
# I purposely made grouplab and collab have a space in case that changes anything. 

在函数之外，相关部分将简单地读作:mtcars <- mtcars %>% rename("Vehicle Cylinders" = cyl, "Vehicle Gears" = gear)

Outside of functions, the relevant part would read simply: mtcars <- mtcars %>% rename("Vehicle Cylinders" = cyl, "Vehicle Gears" = gear)

我一定对重命名在函数中与函数外部的操作方式感到困惑.有什么建议吗?我愿意接受建议.

I must be getting tripped up in how renaming operates in a function vs. outside of it. Any advice? I'm open to suggestions.

更新
这是一种方法.我宁愿不把变量名放在字符串中，但不知道这里的解决方法.接受建议.

UPDATE
Here is one way to do it. I'd rather not put the variable names in strings, but don't know a way around it here. Open to suggestions.

library(tidyverse)
library(xtable)
data(mtcars)

t_groupedfreqprop <- function(df, groupvar, colvar, grouplab, collab, plotname) {
groupvar2 <- rlang::sym(groupvar)
colvar2 <- rlang::sym(colvar)
grouplab <- rlang::sym(grouplab)
collab <- rlang::sym(collab)

t <- df %>%
  select(!!groupvar2, !!colvar2) %>%
  group_by(!!groupvar2, !!colvar2) %>%
  summarise(
    Frequencies = length(!!colvar2),
    Percentages = length(!!colvar2) / nrow(df)
  ) %>%
  mutate(
    Frequencies = scales::comma(Frequencies),
    Percentages = scales::percent(Percentages)
  ) %>%
  rename(
    !!grouplab := !!rlang::sym(groupvar2),
    !!collab := !!rlang::sym(colvar2)
  )

# remainder of function removed
}

t_groupedfreqprop(df = mtcars, groupvar = "gear", colvar = "cyl", grouplab = "Vehicle Gears", collab = "Vehicle Cylinders")

推荐答案

如果您想在表达式的 LHS 上以编程方式分配名称，请使用 :=.

Use := if you want programmatically-assigned names on the LHS of expressions.

x <- "mpg"
xnew <- "mpg2"
rename(mtcars, !!xnew := !!rlang::sym(x))

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