使用正常评估重命名 r 中函数内部的变量

Question

假设您有以下函数将两种数据框列类型相互比较：

dataframe_test <- function(df1, df2) {

  varnames <- names(df1)[names(df1) %in% names(df2)]
  out <- data.frame(
             df1 = sapply(df1[,varnames], class),
             df2 = sapply(df2[,varnames], class)
             ) 
  out$Test <- ifelse(out$df1 == out$df2, " - ", "FLAG")

  return(out)

  }

下面是正在使用的函数：

iris2 <- iris

dataframe_test(iris, iris2)

                 df1     df2 Test
Sepal.Length numeric numeric   - 
Sepal.Width  numeric numeric   - 
Petal.Length numeric numeric   - 
Petal.Width  numeric numeric   - 
Species       factor  factor   -

如何重命名该函数的输出列（上面示例中的 iris、iris2），使它们与输入数据帧同名？我尝试过的每一件事都产生了一个错误或另一个错误。例如，

out <- rename_(out, .dots = setNames(list(df1), new))
colnames(out) <- c(glue::glue("{df1}"), glue::glue("{df2}"), "Flag")

但是没有任何效果...

Answer 1

我们可以使用 deparse 和 substitute 来获取数据框名称并按 ifelse 中的位置引用列名称。

dataframe_test <- function(df1, df2) {

   data1 <- deparse(substitute(df1))
   data2 <- deparse(substitute(df2))
   varnames <- names(df1)[names(df1) %in% names(df2)]
   out <- setNames(data.frame(sapply(df1[,varnames], class),
                sapply(df2[,varnames], class)), c(data1, data2))
   out$Test <- ifelse(out[[1]] == out[[2]], " - ", "FLAG")
   return(out)
}

dataframe_test(iris, iris2)

#                iris   iris2 Test
#Sepal.Length numeric numeric   - 
#Sepal.Width  numeric numeric   - 
#Petal.Length numeric numeric   - 
#Petal.Width  numeric numeric   - 
#Species       factor  factor   -

Answer 2

使用deparse()和substitute()将符号转为字符串：

dataframe_test <- function(df1, df2) {

  varnames <- names(df1)[names(df1) %in% names(df2)]
  out <- data.frame(
    df1 = sapply(df1[,varnames], class),
    df2 = sapply(df2[,varnames], class)
  ) 
  out$Test <- ifelse(out$df1 == out$df2, " - ", "FLAG")
  names(out) <- c(deparse(substitute(df1)), deparse(substitute(df2)), "Test")

  return(out)

}

iris2 <- iris

dataframe_test(iris, iris2)
#>                 iris   iris2 Test
#> Sepal.Length numeric numeric   - 
#> Sepal.Width  numeric numeric   - 
#> Petal.Length numeric numeric   - 
#> Petal.Width  numeric numeric   - 
#> Species       factor  factor   -

^{由 reprex package (v0.3.0)}

于 2020-04-22 创建

使用正常评估重命名 r 中函数内部的变量

Rename variable inside function in r using normal evaluation

r

function

evaluation