按列拆分data.frame并将每列存储为对象，列名称作为对象的名称

HI this is a fundamental question that I have with R. I know there might be solutions out there to do my task, but I would like to ask why could my function wont work.

嗨这是我与R有关的一个基本问题。我知道可能有解决方案来完成我的任务，但我想问为什么我的功能不会起作用。

I have a data.frame that looks like this

我有一个看起来像这样的data.frame

A B C
1 2 3
2 3 4

and I want to store each of values in A, B or C into individual objects with names A, B and C.

我想将A，B或C中的每个值存储到名称为A，B和C的单个对象中。

So here my function

所以我的功能

splitcolnames<-function(x)
  {for (i in colnames(x)){
    subset(x, select=c(i))->i}}
}

But it doesn't work. Can someone be kind and point out what did I not get right?

但它不起作用。有人可以善良，并指出我不对的是什么？

2 个解决方案

#1

One of the following should do it for you, assuming your data.frame is named "mydf".

假设您的data.frame名为“mydf”，则下列之一应该为您完成。

lapply(names(mydf), function(x) assign(x, mydf[x], envir = .GlobalEnv))
lapply(names(mydf), function(x) assign(x, mydf[, x], envir = .GlobalEnv))

The first will create single-column data.frames, and the second will create vectors.

第一个将创建单列data.frames，第二个将创建向量。

Example in a clean session:

干净会话中的示例：

> rm(list = ls())
> ls()
character(0)
> mydf <- data.frame(A = c(1, 2), B = c(3, 4))
> mydf
  A B
1 1 3
2 2 4
> invisible(lapply(names(mydf), function(x) assign(x, mydf[x], envir = .GlobalEnv)))
> ls()
[1] "A"    "B"    "mydf"
> A
  A
1 1
2 2
> rm(list = ls())
> mydf <- data.frame(A = c(1, 2), B = c(3, 4))
> invisible(lapply(names(mydf), function(x) assign(x, mydf[, x], envir = .GlobalEnv)))
> ls()
[1] "A"    "B"    "mydf"
> B
[1] 3 4

In the examples above in invisible to suppress the output.

在上面的例子中，隐形输出无形。

#2

while I agree with @RomanLustrik s comment that this is probably not a good idea, the function you are looking for is assign

虽然我同意@RomanLustrik的评论，这可能不是一个好主意，你正在寻找的功能是分配

for (i in colnames(x)) 
  assign(i, subset(x, select=i))

> A
#   A
# 1 1
# 2 2

> B
#   B
# 1 2
# 2 3

that being said, are you aware of the attach function?

话虽如此，你知道附加功能吗？

 ?attach

#1