Jocelyn,
In a partial answer to your question, try setting gap=0 in the
calls to pairs. This will make the plots closer together.
(You might also find pairs.panels in the psych package useful, --
it implements one of the help examples for pairs to report the
histogram on the diagonal and reports the correlations in the upper
off diagonal).
On a Mac, I just tried setting
quartz(width=30, height=30) #make a big graphics window
#then
library(psych)
my.data <- sim.item(24) #create 500 cases of 24 variables
pairs.panels(my.data, gap=0) #the gap =0 makes the plots right next
to each other
#And then save the graphics window as a pdf. I can open this in a
pdf and scroll around pretty easily.
Bill
At 5:21 AM +0100 8/31/10, Jocelyn Paine wrote:
I've got a data frame with 23 columns, and wanted to plot a
scatterplot matrix of it. I called
pairs( df )
where 'df' is my data frame. This did generate the matrix, but the
plotting window did not expand to make the individual plots large
enough to see. Each one was only about 10 pixels high and wide.
I tried sending the plot to a file, with a high and wide image, by doing
png( "plot.png", width = 4000, height = 4000 )
but I got these errors:
Error in png( "plot.png", width = 4000, height = 4000 ) :
unable to start device
In addition: Warning messages:
1: In png( "plot.png", width = 4000, height = 4000 ) :
Unable to allocate bitmap
2: In png( "plot.png", width = 4000, height = 4000 ) :
opening device failed
The messages aren't helpful, because they don't tell you _why_ R
can't start the device, allocate it, or open it. The documentation
for png says:
Windows imposes limits on the size of bitmaps: these are not documented
in the SDK and may depend on the version of Windows. It seems that width
and height are each limited to 2^15-1.
However, 2^15-1 is 32767, so that isn't the problem here. I tried
various values for height and width. 2400 was OK, but 2500 wasn't.
So it seems R can't produce plots that are more than about 2400
pixels square. This is with R 2.10.1.
Why is png failing on big images? Also, what's the recommended way
to make a file containing a scatterplot matrix when you have lots of
variables? 'pairs' is a very useful function, but obviously one does
need to be careful when doing this, and I don't know what experts
would recommend. Do you loop round the variables plotting each pair
to a different file? I was hoping that I could put them all into one
very big image and view parts of it at a time.
Thanks,
Jocelyn Paine
http://www.j-paine.org
http://www.spreadsheet-parts.org
+44 (0)7768 534 091
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--
William Revelle http://personality-project.org/revelle.html
Professor http://personality-project.org
Department of Psychology http://www.wcas.northwestern.edu/psych/
Northwestern University http://www.northwestern.edu/
Use R for psychology http://personality-project.org/r
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and provide commented, minimal, self-contained, reproducible code.