R help - Nov 2006 - Better y-axis labels, and x-axis scaling

Hello

I'm plotting some data using matplot with a logarithmic scale on the
y-axis. This is the call to matplot I'm using:

  matplot(turns, distances, type = "l", log = "y", lty =
"solid",
          ylab = "", xlab = "Time steps", col =
c("black"))

The values for the 'distances' vector are always between 0 and 1.

The result can be seen at

  http://sneakymustard.com/tmp/plot.jpg

As you can see, the default y axis labels are not very nice, as it uses
irregular intervals.

I tried using variations of

  axis(2, at = pretty(c(0, ceiling(max(distances))), 5))

or

  yaxp = c(round(mind, 2), round(maxd, 2), -4)

in the matplot() call.

Is there anything else I could try for better labeling of values between
0 and 1 in a log-scale axis? Hints or pointers to the appropriate docs
are appreciated :)

Also, is there a command/option to change the plotted spacing between
the labels in a plot? In the plot above, I'd like to make the space
between each label in the x-axis smaller (maybe something similar to the
width/space options in barplot()).

Thanks in advance,
Andre

Andre Nathan <andre <at> digirati.com.br> writes:
> 
> Hello
> 
> I'm plotting some data using matplot with a logarithmic scale on the
> y-axis. This is the call to matplot I'm using:
> 
>   matplot(turns, distances, type = "l", log = "y", lty
= "solid",
>           ylab = "", xlab = "Time steps", col =
c("black"))
> 

  Hmmm.  What do you mean by "not very nice"?  This graph
seems (to me) to be a typical logarithmic scaling axis.
If you really wanted equal scaling you could do

matplot(...,axes=FALSE)
axis(side=1)
pvec <- 10^seq(-3,-1,by=0.5)
axis(side=2,at=pvec,labels=round(pvec,3))
box()

 or something like that...

  warning, totally untested ...

  (the only way I can think of to get "pretty"
and equally spaced ticks is to use ONLY powers
of ten ...)

  Ben Bolker

On Thu, 2006-11-02 at 23:10 +0000, Ben Bolker wrote:
> If you really wanted equal scaling you could do
[...]

Thanks Ben. Do you know how the the x axis can be made shorter?

Best regards,
Andre

Andre Nathan <andre <at> digirati.com.br> writes:
> Thanks Ben. Do you know how the the x axis can be made shorter?
If you want to shorten the x interval, use xlim=c(0,750)
Otherwise, if you want to decrease the physical width of your plot, you should 
use the width= argument in call to "png", when initializing your
plotting
device.