删除功能内的数据帧列 [英] Delete data frame column within function

问题描述

我有以下代码：

df<- iris

library(svDialogs)
columnFunction <- function (x) {
  column.D <- dlgList(names(x), multiple = T, title = "Spalten auswaehlen")$res
  if (!length((column.D))) {
    cat("No column selected\n")
  } else {
    cat("The following columns are choosen:\n")
    print(column.D)
    for (z in column.D) { 
      x[[z]] <- NULL #with this part I wanted to delete the above selected columns
    }
  }
}

columnFunction(df)

那么如何可以动态地解决data.frame列： x [[z]]< - NULL 应该转换为：

So how is it possible to address data.frame columns "dynamically" so: x[[z]] <- NULL should translate to:

df$Species <- NULL
df[["Species"]] <- NULL
df[,"Species"] <- NULL

，并为每个选定的列选择功能。
有没有人知道如何归档这样的东西？我尝试过几个东西，就像使用粘贴命令或 sprintf，deparse ，但我没有得到它的工作。我也绑定，通过使用< < - 将data.frame作为全局变量，但也没有帮助。 （这是我第一次甚至听说过）。看起来我错过了将x和z传递给变量赋值的正确方法。

and that for every selected column in every data.frame chosen for the function. Well does anyone know how to archive something like that? I tried several things like with the paste command or sprintf, deparse but i didnt get it working. I also tied to address the data.frame as a global variable by using <<- but didn`t help, too. (Well its the first time i even heard about that). It looks like i miss the right method transferring x and z to the variable assignment.

推荐答案

如果要创建一个函数 columnFunction 传递的数据框 df ，所有您需要做的是将数据框传递给函数，返回修改版本的 df ，并将结果替换为 df ：

If you want to create a function columnFunction that removes columns from a passed data frame df, all you need to do is pass the data frame to the function, return the modified version of df, and replace df with the result:

library(svDialogs)
columnFunction <- function (x) {
  column.D <- dlgList(names(x), multiple = T, title = "Spalten auswaehlen")$res
  if (!length((column.D))) {
    cat("No column selected\n")
  } else {
    cat("The following columns are choosen:\n")
    print(column.D)
    x <- x[,!names(x) %in% column.D]
  }
  return(x)
}

df <- columnFunction(df)

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