R help - Feb 2009 - Problem with plotting data from within a function

Dear List,

I try to develop code where plotting functions are embeded in my own
functions.  The following is simplified example:
> test <- function() {
>    data <- data.frame(x=rep(1:2, each=50), y=rnorm(100))
>   library(lattice)
>    attach(data)
>    xyplot(y~x)
>    detach()
>}
>test()

As far as I understand R, when test is called this should create one local
data frame, attach it that it's columns are available directly, load the
lattice library, plot data, and then detach the data frame.  But, when I
call test, nothing happens.  I see not plot and no error message.  When I
try the script from Rscript, nothing happens too.  But when I copy the
inside code from test and run it directly, all seems to work.  What am I
doing wrong?  Is this a question to be asked here, or to the developers of
lattice package?

Mvh.
Marie

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Marie Sivertsen wrote:
> Dear List,
> 
> I try to develop code where plotting functions are embeded in my own
> functions.  The following is simplified example:
> 
>> test <- function() {
>>    data <- data.frame(x=rep(1:2, each=50), y=rnorm(100))
>>   library(lattice)
>>    attach(data)
>>    xyplot(y~x)
>>    detach()
>> }
>> test()
> 
> 
> As far as I understand R, when test is called this should create one local
> data frame, attach it that it's columns are available directly, load
the
> lattice library, plot data, and then detach the data frame.  But, when I
> call test, nothing happens.  I see not plot and no error message.  When I
> try the script from Rscript, nothing happens too.  But when I copy the
> inside code from test and run it directly, all seems to work.  What am I
> doing wrong?  Is this a question to be asked here, or to the developers of
> lattice package?
You need to print() your plot:

http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-do-lattice_002ftrellis-graphics-not-work_003f

It is probably OK to ask elementary questions on widely used packages
here. Actual bug reports should go to the maintainers and for
"specialist" questions, you might consider the relevant R-SIG-* group
(of which in this case there appears to be none, but there would be one
for, say, genetic marker analysis).


-- 
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