[R] setting the steps for x axis labels on plot

Jim Lemon jim at bitwrit.com.au
Mon Mar 1 12:37:42 CET 2010

On 03/01/2010 10:16 PM, Gonzalo Garcia-Perate wrote:
> Hello, I'm new to R, I've been working with it for the last 2 weeks. I
> am plotting some data and not getting the labels on the x axis I am
> expecting on my plot.
> my code reads
> #hours in the day
> h <- c(0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23)
> #hp is a data frame with a pivot table of 25 columns (label and data for
> 24 hours)
> plot(h, as.matrix(hp[1,2:25]), main = hp[1,1], type="l", xlim=c(0,23),
> ylim=c(0,1800), xlab="hour", ylab="visitor activity")
> the result you can see here:
> http://www.flickr.com/photos/gonzillaaa/4397357491/
> I was hoping the steps on the x axis would be every hour or at least
> every two hours I am getting unevenly spaced steps (0, 5, 10, 20) instead.
> apologies if this is too obvious a question, I've looked around on
> documentation etc. but found no reference to this.
Hi Gonzalo,
The plotting functions try to space the axis tick labels so that there 
is no crowding or overlapping. One way to get around this is to not 
display the x axis on the initial plot (xaxt="n") and then add a custom 
axis. One function that you can use is staxlab in the plotrix package.


although you may want nlines=3 if you are willing to adjust the x axis 


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