[R] How to rotate the axisnames in a BARPLOT

[Marc Schwartz (via MN)]

On Thu, 2005-06-30 at 23:05 +0200, hulubu at gmx.de wrote:
> Hi all,
> 
> - how can I do a barplot with rotated axis labels? I've seen the example for
> just a plot in the FAQ, but I'll missing the coordinates to plot my text at
> the right position beneath the bars. 
> Is there any (easy?) solution?
> 
> - how can I set the y-axis in a barplot to logarithmic scale?
> 
> Many thanks in advance!
> 
> Best Regards
>  Tom

The same concept for rotating axis labels in a regular plot per the FAQ
can be used in a barplot, as long as you know that barplot() returns the
bar midpoints. So:

     ## Increase bottom margin to make room for rotated labels
     par(mar = c(7, 4, 4, 2) + 0.1)

     ## Create plot and get bar midpoints in 'mp'
     mp <- barplot(1:10)

     ## Set up x axis with tick marks alone
     axis(1, at = mp, labels = FALSE)

     ## Create some text labels
     labels <- paste("Label", 1:10, sep = " ")

     ## Plot x axis labels at mp
     text(mp, par("usr")[3] - 0.5, srt = 45, adj = 1,
          labels = labels, xpd = TRUE)

     ## Plot x axis label at line 4
     mtext(1, text = "X Axis Label", line = 4)

See ?barplot for more information.

With respect to the log scales, you would need to use barplot2(), which
is in the 'gplots' package on CRAN. barplot2() supports log scales using
the same 'log' argument as plot().

HTH,

Marc Schwartz