plyr and ggplot and environments

[Andreas Leha]

Hi all,

I have fallen repeatedly into this: How can I produce a plot inside a,
say, =llply= which uses a local variable that is defined inside the
llply?

Here is an example:
--8<---------------cut here---------------start------------->8---
library("plyr")
library("ggplot2")

testlist <- list("aaa", "bbb")

testplots <-
llply(testlist, function(label)
{
p <- ggplot(data.frame(x=1:10, y=1:10)) + geom_point(aes(x=x, y=y))
p <- p + geom_text(aes(x=0.5, y=0.5, label=label))
p
})

testplots[[1]]
## Error in eval(expr, envir, enclos) : object 'label' not found


## NB: the version outside an llply works:
label <- "aaa"
p <- ggplot(data.frame(x=1:10, y=1:10)) + geom_point(aes(x=x, y=y))
p <- p + geom_text(aes(x=0.5, y=0.5, label=label))
p
--8<---------------cut here---------------end--------------->8---


What is the proposed solution here?

Regards,
Andreas

[Andreas Leha]

Andreas Leha

<andrea...@med.uni-goettingen.de> writes:

> Hi all,
>
> I have fallen repeatedly into this: How can I produce a plot inside a,
> say, =llply= which uses a local variable that is defined inside the
> llply?
>
> Here is an example:

> library("plyr")
> library("ggplot2")
>
> testlist <- list("aaa", "bbb")
>
> testplots <-
> llply(testlist, function(label)
> {
> p <- ggplot(data.frame(x=1:10, y=1:10)) + geom_point(aes(x=x, y=y))
> p <- p + geom_text(aes(x=0.5, y=0.5, label=label))
> p
> })
>
> testplots[[1]]
> ## Error in eval(expr, envir, enclos) : object 'label' not found
>
>
> ## NB: the version outside an llply works:
> label <- "aaa"
> p <- ggplot(data.frame(x=1:10, y=1:10)) + geom_point(aes(x=x, y=y))
> p <- p + geom_text(aes(x=0.5, y=0.5, label=label))
> p
>
>

> What is the proposed solution here?
>
> Regards,
> Andreas

Sorry to answer my own post.

The solution in that case is simple, of course. I just have to pass the
used data as data=xxx.

I'll come back, if I find one of my previous examples with no obvious
solution.

Until then, sorry for the noise.

- Andreas

[David Guy]

Andrea,

I think the problem is that the label=label must be taken outside the aes of geom_text. Then it works fine.

David

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