R help - Sep 2004 - pointsize in png graphics

Dear all,

I'm trying to produce 2 png files, one consisting of an image plot and a
color-table (also an image plot) and the other one consisting of 4 image
plots and a color table. I'd like the color table to be exactly the same.
The way I proceded is the following:

for one plot and the color-table
png(file = png.file, width = 650, height = 800, pointsize = 16)
layout(matrix(c(1, 2), ncol = 2, nrow = 1, byrow = T),
       widths = c(6, 1), heights = 1)
par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
...
dev.off()

for 4 plots and the color-table
png(file = png.file, width = 650, height = 800, pointsize = 16)
layout(matrix(c(1, 2, 5, 3, 4, 5), ncol = 3, nrow = 2, byrow = T),
       widths = c(3, 3, 1), heights = c(1, 1))
par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
...
dev.off()

The only difference is the layout of the plot. The outcome though is
completely different. It seems that the definition of the size of one point
is different in the two plots as the graphics with 4 plots and color table
has smaller fonts and smaller margins. What do I have to do to be sure the
size of the fonts is the same in two different png graphcis of exactly the
same size when the pointsize is the same?

I'm working with Windows XP and tried both running the R script as a batch
job and running it within Emacs with ESS.
> version
         _
platform i386-pc-mingw32
arch     i386
os       mingw32
system   i386, mingw32
status
major    1
minor    9.1
year     2004
month    06
day      21
language R

Many thanks in advance and best regards, Jan:-)

Jan.Kleinn at partnerre.com wrote:
> Dear all,
> 
> I'm trying to produce 2 png files, one consisting of an image plot and
a
> color-table (also an image plot) and the other one consisting of 4 image
> plots and a color table. I'd like the color table to be exactly the
same.
> The way I proceded is the following:
> 
> for one plot and the color-table
> png(file = png.file, width = 650, height = 800, pointsize = 16)
> layout(matrix(c(1, 2), ncol = 2, nrow = 1, byrow = T),
>        widths = c(6, 1), heights = 1)
> par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
> ...
> dev.off()
> 
> for 4 plots and the color-table
> png(file = png.file, width = 650, height = 800, pointsize = 16)
> layout(matrix(c(1, 2, 5, 3, 4, 5), ncol = 3, nrow = 2, byrow = T),
>        widths = c(3, 3, 1), heights = c(1, 1))
> par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
> ...
> dev.off()
> 
> The only difference is the layout of the plot. The outcome though is
> completely different. It seems that the definition of the size of one point
> is different in the two plots as the graphics with 4 plots and color table
> has smaller fonts and smaller margins. What do I have to do to be sure the
> size of the fonts is the same in two different png graphcis of exactly the
> same size when the pointsize is the same?
> 
> I'm working with Windows XP and tried both running the R script as a
batch
> job and running it within Emacs with ESS.
> 
> 
>>version
> 
>          _
> platform i386-pc-mingw32
> arch     i386
> os       mingw32
> system   i386, mingw32
> status
> major    1
> minor    9.1
> year     2004
> month    06
> day      21
> language R
> 
> Many thanks in advance and best regards, Jan:-)
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
> 
Hi Jan,

Generally, I've found it very undesirable to set pointsize when calling 
a graphics device. Instead, I set the cex parameter, either globally 
through "par" or for each individual plot. If you don't tweak the 
defaults, then cex effectively works in picas, so you can divide your 
desired point size by 12 to come up with the right value of cex. Why 
don't you give that a try and let me know how it turns out?

Also, are you sure that you managed to run that code as a batched 
script? png() is one of the graphics devices that doesn't work in batch. 
To get batched pngs, I typically have to use bitmap(type = "png16m",
...).

Kevin

Hi


Jan.Kleinn at partnerre.com wrote:
> Dear all,
> 
> I'm trying to produce 2 png files, one consisting of an image plot and
a
> color-table (also an image plot) and the other one consisting of 4 image
> plots and a color table. I'd like the color table to be exactly the
same.
> The way I proceded is the following:
> 
> for one plot and the color-table
> png(file = png.file, width = 650, height = 800, pointsize = 16)
> layout(matrix(c(1, 2), ncol = 2, nrow = 1, byrow = T),
>        widths = c(6, 1), heights = 1)
> par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
> ...
> dev.off()
> 
> for 4 plots and the color-table
> png(file = png.file, width = 650, height = 800, pointsize = 16)
> layout(matrix(c(1, 2, 5, 3, 4, 5), ncol = 3, nrow = 2, byrow = T),
>        widths = c(3, 3, 1), heights = c(1, 1))
> par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
> ...
> dev.off()
> 
> The only difference is the layout of the plot. The outcome though is
> completely different. It seems that the definition of the size of one point
> is different in the two plots as the graphics with 4 plots and color table
> has smaller fonts and smaller margins. What do I have to do to be sure the
> size of the fonts is the same in two different png graphcis of exactly the
> same size when the pointsize is the same?
> 
> I'm working with Windows XP and tried both running the R script as a
batch
> job and running it within Emacs with ESS.

I think the problem is that R is trying to think for you.  R 
automatically reduces text size when there are more than three plots (or 
more than three cells in a layout) on a page.  Below are two suggestions 
for making the two layouts the same:


# dummy image plot
dummyplot <- function(col) {
   plot.new()
   usr <- par("usr")
   rect(usr[1], usr[3], usr[2], usr[4], col=col)
}

# original problem
x11()
layout(matrix(c(1, 2), ncol = 2, nrow = 1, byrow = T),
        widths = c(6, 1), heights = 1)
par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
dummyplot("orange")
dummyplot("blue")

x11()
layout(matrix(c(1, 2, 5, 3, 4, 5), ncol = 3, nrow = 2, byrow = T),
        widths = c(3, 3, 1), heights = c(1, 1))
par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
dummyplot("red")
dummyplot("yellow")
dummyplot("pink")
dummyplot("violet")
dummyplot("blue")

# solution 1: make second layout same as first
# leave first page alone
# revert auto cex decrease on second page
x11()
layout(matrix(c(1, 2), ncol = 2, nrow = 1, byrow = T),
        widths = c(6, 1), heights = 1)
par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
dummyplot("orange")
dummyplot("blue")

x11()
layout(matrix(c(1, 2, 5, 3, 4, 5), ncol = 3, nrow = 2, byrow = T),
        widths = c(3, 3, 1), heights = c(1, 1))
par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0,
     ### CHANGES HERE
     cex=1.5, mex=0.66)
dummyplot("red")
dummyplot("yellow")
dummyplot("pink")
dummyplot("violet")
dummyplot("blue")

# solution 2: make first layout same as second
# make same number of columns/rows in first layout
# leave second page alone
x11()
layout(### CHANGES HERE
        matrix(c(1, 1, 2, 1, 1, 2), ncol = 3, nrow = 2, byrow = T),
        widths = c(6, 1), heights = 1)
par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
dummyplot("orange")
dummyplot("blue")

x11()
layout(matrix(c(1, 2, 5, 3, 4, 5), ncol = 3, nrow = 2, byrow = T),
        widths = c(3, 3, 1), heights = c(1, 1))
par(mar = c(0.2, 0.2, 0.2, 0.2), mgp = c(2, 1, 0), las = 0)
dummyplot("red")
dummyplot("yellow")
dummyplot("pink")
dummyplot("violet")
dummyplot("blue")

Paul
-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/