
I have run into some surprising behaviour when plotting data in a 3x2
grid:
random parts of the data on my graphs aren't rendered. Not on screen,
not on file,
and not when I send the plot to a printer. I don't get any error
messages either.
 
When I do the individual plots (not in a grid) they are each rendered
correctly.
 

My questions are:
 - Has anyone encountered something like this, or is it particular to my
   installation?
 - Have I hit one of R's limits, and can I increase that limit?
 - Would there be any workarounds that will allow me to get those 6
graphs
   in one single plot without thinning the data?
 
 
The circumstances of the problem are:
 
The data I am plotting consists of 4 dataframes and 4 strings:
 
d1 - d4 are dataframes of dimension 308160 x 21 that contain a column
named "det_ok_num".
BPS1 - BPS4 are strings
 
I'm running R 1.51 under Windows XP and I have 2 Gb of core memory, 800
Mb free, and 5 Gb swappable. 
All variables are in memory; the total amount of memory used by the Rgui
process is slightly less than 400Mb. 
 

The plot command I use is
Fplot6_Det_OK (d1, d2, d3, d4, d1, d2, BPS1, BPS2, BPS3, BPS4, BPS1,
BPS2)
 
I am using the following two small plot functions:
 
Fplot6_Det_OK = function(d1, d2, d3, d4, d5, d6, BPS1, BPS2, BPS3, BPS4,
BPS5, BPS6) {
# Purpose: Plot detector status for MONICA loops
#          make 3x2 subplot window and plot 6 loops
#
#
 
op <- par(no.readonly = TRUE)
 
par_plot6 <- par(mfrow = c(3, 2))
 
FplotDetOK (d1, BPS1)
FplotDetOK (d2, BPS2)
FplotDetOK (d3, BPS3)
FplotDetOK (d4, BPS4)
FplotDetOK (d5, BPS5)
FplotDetOK (d6, BPS6)
 
par(op)
}
 
 
 FplotDetOK = function(d, BPS) {
# Purpose: Plot detector status for MONICA loops
#
#
 
subtitleStr = paste ("BPS = ", BPS)
plot(d$det_ok_num, pch=".", col="blue", sub = subtitleStr)
}

 
Charles Lindveld
Centre for Transport Studies
Imperial College London
 

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