Re: [R] Overlapping grid in plot

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Sun 16 Jan 2005 - 21:00:36 EST

On Sun, 16 Jan 2005 10:05:01 +0100, "Robin Gruna" <robin_gruna@hotmail.com> wrote :

>Ok, here is some sample code to my problem
>
>> barplot(c(1,2,4,3,2), legend.text = "Legend")
>> grid()
>
>..the lines are crossing my barchart :-(...

The reason for this is the way R thinks of graphics, essentially as ways to put ink on paper. You draw the grid on top of the existing plot.

Getting it to look the way you want is a little tricky: you want to draw the grid first so the bars appear on top, but R won't know how to draw the grid until it has drawn the plot. So the solution is to draw the plot twice, e.g.

barplot(c(1,2,4,3,2), legend.text = "Legend") grid(col='black', lty='solid')

oldpar <- par(bg='white')

# this says to use a solid white background 
# instead of the default one, which is usually transparent.  The
# old colour is saved in oldpar

par(new=T)
# this says to overwrite the plot

barplot(c(1,2,4,3,2), legend.text = "Legend") par(oldpar) # restore the old colour

Duncan Murdoch

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