Dear all,
One for the windows graphics developers I guess....
I seem to have hit a bug in the line drawing in windows (default
device or explicit calls to win.metafile). As the line segments used
to plot a curve get smaller (increased resolution) the line drawn
seems to get less smooth rather than more smooth, and starts to
break up.. Attached is a toy example drawing a quadratic with
increasing resolution. In my real example - a plot for publication - it
is very difficult to find a compromise where the line segments are
close enough to give a smooth-looking curve without the thing
breaking down. Look like a bug or feature in plotting small line
segments? Using pdf() seems to be OK which suggests a windows
driver issue - I dimly recall something about wmf and maybe emf
having an implicit resolution, despite being a vector format. I have
also noticed that filled symbols (eg pch=16) are not always
completely filled, but haven't an example to demonstrate this.
Keep up the good work!
Steve.
------------------------example----------------------------------
#axes and text rendered well
plot(c(0,22),c(0,100),xlab="X-axis",ylab="Y-axis",type="n")
#lines with large segments
x<-0:10
y<-x^2
for (delta in 1:4) lines(x+delta,y,lwd=delta,type="l")
#more detailed lines
x<-seq(0,10,by=.1)
y<-x^2
for (delta in 1:4) lines(x+4+delta,y,lwd=delta,type="l")
#even more detailed lines
x<-seq(0,10,by=.01)
y<-x^2
for (delta in 1:4) lines(x+8+delta,y,lwd=delta,type="l")
--------------------------------------------------------------------------------------------
Dr Steve Roberts
steve.roberts@man.ac.uk
Senior Lecturer in Medical Statistics,
CMMCH NHS Trust and University of Manchester Biostatistics Group,
0161 275 5192 / 0161 276 5785
