如何使用变量在ggplot中指定列名 [英] How to use a variable to specify column name in ggplot

问题描述

我有一个 ggplot 命令

I have a ggplot command

ggplot( rates.by.groups, aes(x=name, y=rate, colour=majr, group=majr) )

在函数内部.但我希望能够使用函数的参数来挑选要用作颜色和组的列.IE.我想要这样的东西

inside a function. But I would like to be able to use a parameter of the function to pick out the column to use as colour and group. I.e. I would like something like this

f <- function( column ) {
    ...
    ggplot( rates.by.groups, aes(x=name, y=rate, colour= ??? , group=??? ) )
}

这样ggplot中使用的列是由参数决定的.例如.对于 f("majr") 我们得到了

So that the column used in the ggplot is determined by the parameter. E.g. for f("majr") we get the effect of

ggplot( rates.by.groups, aes(x=name, y=rate, colour=majr, group=majr) )

但是对于 f("gender") 我们得到的效果是

but for f("gender") we get the effect of

  ggplot( rates.by.groups, aes(x=name, y=rate, colour=gender, group=gender) )

我尝试过的一些事情:

ggplot( rates.by.groups, aes(x=name, y=rate, colour= columnName , group=columnName ) )

没有用.也没有

e <- environment() 
ggplot( rates.by.groups, aes(x=name, y=rate, colour= columnName , group=columnName ), environment=e )

推荐答案

你可以使用aes_string:

f <- function( column ) {
    ...
    ggplot( rates.by.groups, aes_string(x="name", y="rate", colour= column,
                                        group=column ) )
}

只要您将列作为字符串传递给函数(f("majr") 而不是 f(majr)).另请注意，我们将其他列 "name" 和 "rate" 更改为字符串.

as long as you pass the column to the function as a string (f("majr") rather than f(majr)). Also note that we changed the other columns, "name" and "rate", to be strings.

如果出于某种原因您不想使用 aes_string，您可以将其更改为(稍微麻烦一些):

If for whatever reason you'd rather not use aes_string, you could change it to (the somewhat more cumbersome):

    ggplot( rates.by.groups, aes(x=name, y=rate, colour= get(column),
                                        group=get(column) ) )

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