[R] PDF too large, PNG bad quality

[Jim Lemon]

On 10/23/2009 06:07 AM, Lasse Kliemann wrote:
> I wish to save a scatter plot comprising approx. 2 million points
> in order to include it in a LaTeX document.
>
> Using 'pdf(...)' produces a file of size about 20 MB, which is
> useless.
>
> Using 'cairo_pdf(...)' produces a smaller file, around 3 MB. This
> is still too large. Not only that the document will be too large,
> but also PDF viewers choke on this. Moreover, Cairo has problems
> with text: by default text looks ugly, like scaled bitmaps. After
> hours of trying different settings, I discovered that choosing a
> different font family can help, e.g.: 'par(family="Mono")'. This
> gives good-looking text. Yet, the problem with the file size
> remains.
>
> There exists the hint to produdc EPS instead and then convert to
> PDF using 'epstopdf'. The resulting PDF files are slightly
> smaller, but still too large, and PDF viewers still don't like
> it.
>
> So I gave PNG a try. PNG files are much smaller and PDF viewers
> have no trouble with them. However, fonts look ugly. The same
> trick that worked for Cairo PDF has no effect for PNG. When I
> view the PNGs with a dedicated viewer like 'qiv', even the fonts
> look good. But not when included in LaTeX; I simply use
> '\includegraphics{...}' and run the document through 'pdflatex'.
>
> I tried both, creating PNG with 'png(...)' and converting from
> PDF to PNG using 'convert' from ImageMagick.
>
> So my questions are:
>
> - Is there a way to produce sufficiently lean PDFs directly in R,
>    even when the plot comprises several million points?
>
> - How to produce a PNG that still looks nice when included in a
>    LaTeX PDF document?
>
> Any hints will be greatly appreciated.
>    
Hi Lasse,
I may be right off the track, but I can't make much sense of 2 million 
points in a scatterplot. If you are interested in the density of points 
within the plot, you could compute this using something like the bkde2 
function in the KernSmooth package and then plot that using something 
like "image".

Jim