special characters in column names

[july]

Hi there,

my data frame has columns with special characters, e.g.:

df <- data.frame(c(1:10),c(10:1))
names(df) <- c("Special name(1)","Special name(2)")

then, I have a variable containing the name of the column which should
be plotted:

plot.Column <- "Special name(2)"

I'd like to use this variable to generate my plot. Instead of writing
this:

ggplot(df, aes(y = `Special name(2)`, x = `Special name(2)`)) +
geom_point()

I'd like to write something like this (this does not work, I know but
maybe you see what I want to do):

ggplot(df, aes(y = plot.Column, x = plotColumn)) + geom_point()


Is it possible? How?

Antje

[july]

I think, I found a solution, but I have to change the labeling on the
y-axis (now "get(plot.Column)") by adding the scale_y_...name

ggplot(df, aes(y = get(plot.Column), x = get(plot.Column))) +
geom_point()

If you know any other solution, let me know.

[Luciano Selzer]

Have a look at aes_string.

 

HTH
Luciano

2011/5/6 july <antje.ni...@googlemail.com>

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[july]

I've tried it but something was wrong. I could not get it working...
Could you please provide me example code for my example dataset?

Antje

On 6 Mai, 17:59, Luciano Selzer <luciano.sel...@gmail.com> wrote:
> Have a look at aes_string.
>
> HTH
> Luciano
>

> 2011/5/6 july <antje.niederl...@googlemail.com>

[july]

I've tested it once more. It does not work with aes_string. Is there
anything wrong?:

library(ggplot2)

df <- data.frame(c(1:10),c(10:1))

# works with simple column names
names(df) <- c("name1","name2")
parameter <- "name1"
ggplot(df, aes_string(x = parameter, y = parameter)) + geom_point()

# does not work with special characters in column names

names(df) <- c("Special name(1)","Special name(2)")

parameter <- "Special name(1)"
ggplot(df, aes_string(x = parameter, y = parameter)) + geom_point()

# works like this but then the labeling shows "get(parameter)" instead
of the parameter name
ggplot(df, aes(x = get(parameter), y = get(parameter))) + geom_point()

Ciao,
Antje

[Luciano Selzer]

Well, the issue is with parse and the space in the name. parse produces an expression and if the name has spaces in it then the expression would be treated like two thing instead of a a variable name. I hope this explanation makes sense. I would replace the space with an underscore or a point.

HTH
Luciano

2011/5/9 july <antje.ni...@googlemail.com>

[july]

Thanks a lot for your explanation! I cannot replace the characters
(the plots will be generated automatically and I don't know anything
about column names of the incoming tables). Instead, I will stick to
the solution with get(...) and add the correct labeling by changing
the appropriate scale name.

Ciao,
Antje

On May 9, 3:15 pm, Luciano Selzer <luciano.sel...@gmail.com> wrote:
> Well, the issue is with parse and the space in the name. parse produces an
> expression and if the name has spaces in it then the expression would be
> treated like two thing instead of a a variable name. I hope this explanation
> makes sense. I would replace the space with an underscore or a point.
>
> HTH
> Luciano
>

> 2011/5/9 july <antje.niederl...@googlemail.com>

[Hadley Wickham]

On Mon, May 9, 2011 at 1:51 AM, july <antje.ni...@googlemail.com> wrote:
> I've tested it once more. It does not work with aes_string. Is there
> anything wrong?:
>
> library(ggplot2)
>
> df <- data.frame(c(1:10),c(10:1))
>
> # works with simple column names
> names(df) <- c("name1","name2")
> parameter <- "name1"
> ggplot(df, aes_string(x = parameter, y = parameter)) + geom_point()
>
> # does not work with special characters in column names
> names(df) <- c("Special name(1)","Special name(2)")
> parameter <- "Special name(1)"
> ggplot(df, aes_string(x = parameter, y = parameter)) + geom_point()

You want:

names(df) <- c("Special name(1)","Special name(2)")
parameter <- "`Special name(1)`"
ggplot(df, aes_string(x = parameter, y = parameter)) + geom_point()

When you have non-syntactic names, you need to surround them in `.

Hadley

--
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/