[R] labelling barplot
Marc Schwartz
MSchwartz at MedAnalytics.com
Sat Nov 27 16:22:36 CET 2004
On Sat, 2004-11-27 at 08:59 +0000, Ross Clement wrote:
> Hi. I'd like to produce a barplot where only the lowest value and the
> highest value are labelled on the x-axis. E.g. I might have a list
> of numbers and frequencies:
>
> barplot( c( 2, 2, 0, 4, 2 ), names.arg=c( 1, 2, 3, 4, 5 ) )
>
> where the data is a set of counts for some values between 1 and 5. I'd
> like to have a barplot where only the extremes 1 and 5 are labelled.
>
> How do I do this?
>
> Thanks in anticipation,
>
> Ross Clement
Draw your barplot, saving the bar midpoints in 'mp':
mp <- barplot( c( 2, 2, 0, 4, 2 ))
Now using axis(), label the x axis. Set 'at' to be the first and last
values in the 'mp' vector:
axis(1, labels = c(1, 5), at = c(mp[1], mp[length(mp)]))
Another alternative is to use mtext() instead of axis() like this:
mtext(side = 1, text = c(1, 5), at = c(mp[1], mp[length(mp)]), line = 1)
HTH,
Marc Schwartz
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