[R] Multiple plot jpeg file

[Prof Brian Ripley]

On Tue, 19 Jun 2007, Marc Schwartz wrote:

>
>
> On Tue, 2007-06-19 at 15:39 -0400, Bill Hunsicker wrote:
>> R-Help,
>>
>> I am executing a R script and would like to put multiple plots into a
>> single file. For some reason the contents of plotfile.jpg always seem to
>> contain the last plot and not all plots.
>>
>> If I do same thing with pdf, a multiple plot file is created.
>>
>> Can you help me?
>>
>> Regards,
>> Bill
>
> There is no notion of a 'page' in bitmapped devices as there is with PDF
> or PS devices. Thus, each time you call plot(...) with a bitmapped
> device, the previous output is lost.

But there is a concept of multiple pages in separate files and that is the 
default, Rplot001.jpg, Rplot002.jpg and so on.

The JPEG format only supports one 'page' per file.

> If you want multiple plots in a bitmapped device, you would need to use
> layout() or par(mfrow/mfcol) to define multiple plot regions within the
> overall bitmapped output.
>
> For example:
>
> jpeg("test.jpg", 400, 400)
>
> # Set for 2 rows, 1 col
> par(mfrow = c(2, 1))
>
> # Set the margins to make room
> par(mar = c(1, 4, 4, 2))
>
> # Draw a barplot
> barplot(1:5)
>
> # Set the margins to make room
> par(mar = c(5, 4, 1, 2))
>
> # Do a scatterplot
> plot(1:10)
>
> # Close the device
> dev.off()
>
>
> Adjust other pars as required.
>
> See ?par and ?layout
>
> HTH,
>
> Marc Schwartz
>
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>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595