R help - Apr 2007 - Setting where the x-axis crosses the y-axis

Hi all,

my apologies for a probably very obvious question but i can't figure out if,
on
a bar plot, there is a simple way to have the x-axis cross the y-axis at 1,
when the y-axis is on a log-scale?
I want to draw a bar plot, and have some of the bars "drop" below 1
while
starting from 1. Is this possible?
I have been trying various things using barplot, barplot2 etc... without
success.
Thanks a lot for your help,

stephane

I think you are looking for this

tmp <- abs(rnorm(100, s=8))
ltmp <- log(tmp)
plot(ltmp, type="h", yaxt="n", main="what you
want")
exp(par("usr")[3:4])
par("yaxp")[1:2]
logticks <- axTicks(2, axp=c(10^c(-1,3),3), log=TRUE)
axis(2, at=log(logticks), labels=logticks)
plot(tmp, type="h", log="y", main="standard")

Hi Stephane,

Drawing a bar plot with log axes is a really bad idea.  The whole
point of a bar is that you are judging the area between the top of the
bar and the y-axis.  If you use a log scaled axis the distance to y=0
is Inf, and your plot isn't really meaningul.

You might want to consider using a dot plot instead.  See
http://www.b-eye-network.com/view/index.php?cid=2468&fc=0&frss=1&uafor
a good discussion of the issues.

Hadley

On 4/6/07, stephane helleringer <hellerin at ssc.upenn.edu>
wrote:
> Hi all,
>
> my apologies for a probably very obvious question but i can't figure
out if, on
> a bar plot, there is a simple way to have the x-axis cross the y-axis at 1,
> when the y-axis is on a log-scale?
> I want to draw a bar plot, and have some of the bars "drop" below
1 while
> starting from 1. Is this possible?
> I have been trying various things using barplot, barplot2 etc... without
> success.
> Thanks a lot for your help,
>
> stephane
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>