R help - Apr 2008 - Get inside a function the name of a variable called as argument?

Hi list,
I created a function to plot my data:
plot_function(vector)
I want to write the name of the argument vector in the legend/title of 
the plot.
For example if I call:
 > plot_function(my_vector)
I want "my_vector" to be written in the legend or title and so
retrieve
the name of this object as a string.

Is it possible to achieve this?
Thanks a lot for your help
Julien

-- 
Julien Roux, PhD student
http://www.unil.ch/dee/page22707.html
Department of Ecology and Evolution
Biophore, University of Lausanne, 1015 Lausanne, Switzerland
tel: +41 21 692 4221    fax: +41 21 692 4165

On Tue, Apr 29, 2008 at 03:53:02PM +0200, Julien Roux
wrote:
> Hi list,
> I created a function to plot my data:
> plot_function(vector)
> I want to write the name of the argument vector in the legend/title of 
> the plot.
> For example if I call:
> > plot_function(my_vector)
> I want "my_vector" to be written in the legend or title and so
retrieve
> the name of this object as a string.
> 
> Is it possible to achieve this?
While it might be possible, I think it would be better to use an extra
argument for this:

plot_function(my_vector, title = my_title)

Functions should be general, and relying on the name of the variable
makes your function less general. What if you in the future want to
use plot_function with an anynmous vector created dynamically? e.g by
combining two other vectors:

plot_function(c(foo, bar))

--
Hans Ekbrand (http://sociologi.cjb.net) <hans at sociologi.cjb.net>
GPG Fingerprint: 1408 C8D5 1E7D 4C9C C27E 014F 7C2C 872A 7050 614E
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On 29/04/2008 9:53 AM, Julien Roux wrote:
> Hi list,
> I created a function to plot my data:
> plot_function(vector)
> I want to write the name of the argument vector in the legend/title of 
> the plot.
> For example if I call:
>  > plot_function(my_vector)
> I want "my_vector" to be written in the legend or title and so
retrieve
> the name of this object as a string.
> 
> Is it possible to achieve this?
Yes.  If the argument name is arg in the function definition, then 
substitute(arg) gives the expression that was passed, and 
deparse(substitute(arg)) converts it into a string to use in a title.

e.g.

 > plot_function <- function(arg) {
+   deparse(substitute(arg))
+ }
 > plot_function(my_vector)
[1] "my_vector"

Duncan Murdoch
> Thanks a lot for your help
> Julien
>