[R] adjust scale of x-axis to unequal intervals

[Jim Lemon]

On 09/24/2013 10:05 AM, Sagan Friant wrote:
> Dear R community,
>
> Please help.  I am new(ish) to R and have spent too many hours trying to
> achieve what I believe should be a relatively simple task.  I have searched
> help forums, but have not been able to successfully apply responses to
> loosely related questions to my own.
>
> I am running some preliminary summary statistics.  I wish to create a
> boxplot graph that represents summaries of samples collected over a series
> of time points (0-18).  My sample collection intensity was highest early
> on, with samples collection decreasing in frequency over time.  I am trying
> to scale the the x-axis to unequal intervals.
>
> The code I used for a graph representing a subset of my sample (re-named)
> is below:
>
> Boxplot(ALL~sample, data=rich.small, id.method="n", las = 2, names =
> c("0","2","4","7","10","18"))
>
> There were 10days between samples 0&2 and 3 days between 2&4, 4&7, 7&10,
> and then 75days between 10&18
>
Hi Sagan,
I think what you want is to have the boxplots spaced out as the 
occasions of measurement:

rich.small<-data.frame(ALL=rnorm(240,5),
  sample=c(rep(0,60),rep(2,50),rep(4,40),
  rep(7,30),rep(10,30),rep(18,30)))
# this gives you the spacing with the occasion labels
boxplot(ALL~sample,rich.small,at=c(0,10,13,16,19,94),xaxt="n",
  xlab="Occasion")
library(plotrix)
staxlab(1,at=c(0,10,13,16,19,94),labels=c(0,2,4,7,10,18))
# and this gives you the days
boxplot(ALL~sample,rich.small,at=c(0,10,13,16,19,94),xaxt="n",
  xlab="Days")
staxlab(1,at=c(0,10,13,16,19,94))

Lots of space in the middle for something.

Jim