R help - Apr 2008 - ggplot2: setting global graphic parameters with png driver

Hi all,

I prepared a few charts with ggplot2, and was happy with the results as 
displayed on screen.
I tried to draw them with a PNG driver instead. But I ran into several 
problems while trying to increase the resolution of the picture.

Mainly, when I increased the picture size (e.g png(width=1024, 
height=768) ), the texts (title, labels, etc...) where too small. I 
tried to set the "pointsize" option of the driver. That did the trick,
to some extent. But it seems limited, and I couldn't get big enough 
fonts for high resolution images. Also, I tried the "resolution"
setting
of the driver. But this has an effect on lots of things, e.g. the length 
of the lines in the legend, so I gave up this idea.
I tried to change the font size of all elements, with e.g. 
grid.gedit("label", gp=gpar(cex=4) ). But the position of the labels 
does not change then, and with the bigger font, they are drawn on top of 
the axis or of its title.
Another problem was that the line width is also too small in big images. 
I couldn't find a way to change it globally.

So, is there a way to go easily from a plot that looks good on screen 
(X11 driver) to a similar png image? Or is it possible to change the 
default settings of ggplot2 (line size and font size in particular, 
which are not covered by the ggopt function) ? I guess people usually 
export their charts as image files, so hopefully there's an easy solution.

Many thanks,

Xavier

You forgot to mention your version of R and your platform (and R has at 
least 3 separate png() devices).

In 2.7.0, specify the size in inches and increase the resolution.
In earlier versions, try bitmap().  From NEWS for 2.7.0

     o	Considerable efforts have been made to make the default output
 	from graphics devices as similar as possible (and in
 	particular close to that from postscript/pdf).	Many devices
 	were misinterpreting 'pointsize' in some way, for example as
 	being in device units (pixels) rather than in points.


On Tue, 29 Apr 2008, Xavier Chardon wrote:
> Hi all,
>
> I prepared a few charts with ggplot2, and was happy with the results as 
> displayed on screen.
> I tried to draw them with a PNG driver instead. But I ran into several 
> problems while trying to increase the resolution of the picture.
>
> Mainly, when I increased the picture size (e.g png(width=1024, height=768)
),
> the texts (title, labels, etc...) where too small. I tried to set the 
> "pointsize" option of the driver. That did the trick, to some
extent. But it
> seems limited, and I couldn't get big enough fonts for high resolution 
> images. Also, I tried the "resolution" setting of the driver. But
this has an
> effect on lots of things, e.g. the length of the lines in the legend, so I 
> gave up this idea.
> I tried to change the font size of all elements, with e.g. 
> grid.gedit("label", gp=gpar(cex=4) ). But the position of the
labels does not
> change then, and with the bigger font, they are drawn on top of the axis or
> of its title.
> Another problem was that the line width is also too small in big images. I 
> couldn't find a way to change it globally.
>
> So, is there a way to go easily from a plot that looks good on screen (X11 
> driver) to a similar png image? Or is it possible to change the default 
> settings of ggplot2 (line size and font size in particular, which are not 
> covered by the ggopt function) ? I guess people usually export their charts
> as image files, so hopefully there's an easy solution.
>
> Many thanks,
>
> Xavier
>
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
-- 
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)
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