将字符串转换为R/ggplot2中的函数参数的最佳方法? [英] Best way to convert character strings in to function arguments in R/ggplot2?

问题描述

我正在开发一个闪亮的应用程序，用户可以选择使用ggplot2绘制哪些变量，但是我完全不确定将字符串(这是要绘制的变量的名称)转换为合适的最佳方法函数参数.

I am working on a shiny app where the user selects which variables might be plotted using ggplot2, however I am completely unsure about the best way to convert character strings (which are the names of the variable to be plotted) in to suitable function arguments.

考虑以下非常人为的可行示例:

Consider the following very artificial, working example:

df <- data.frame(gp = factor(rep(letters[1:3], each = 10)),
                 y = rnorm(30))

ggplot(df, aes(x = gp, y = y)) +
   geom_point() + facet_wrap(~gp)

现在，如果我只拥有变量名的字符串，我该如何告诉ggplot在x轴上绘制'gp'变量?

Now, how would I tell ggplot to plot the 'gp' variable on the x axis, if all I have is a character string of the name of the variable?

我已经提出了以下建议，但是有没有更简单，更常规的方法?请注意我在aes()和facet_wrap()函数中使用的不同方法.

I have whipped up the following, but is there a simpler and more conventional method? Note the different approaches I use in the aes() and facet_wrap() functions.

x.var <- "gp"

ggplot(df, aes(x=lol <- switch(x.var,"gp"=gp), y = y)) +
   geom_point() + facet_wrap(as.formula(paste("~",x.var)))

任何见识都将不胜感激！

Any insight is greatly appreciated!

推荐答案

如果使用aes_string而不是x=lol <- switch(x.var,"gp"=gp)来指定x和y变量，那就更好了，即使用以下命令:

It would be much better if you used aes_string to specify your x and y variables, instead of x=lol <- switch(x.var,"gp"=gp), i.e. use the following:

ggplot(df, aes_string(x = x.var, y = 'y')) +
  geom_point() + facet_wrap(as.formula(paste("~",x.var)))

不幸的是，对于facet_wrap函数，您已经完成的操作可能是最佳方法.

Unfortunately, for the facet_wrap function what you have already done is probably the optimal way.

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