[R] Plotting Non Numeric Data

[Marc Schwartz]

On Tue, 2007-11-20 at 00:37 +0000, Michal Charemza wrote:
> Hi,
> 
> Is there a way to plot non numerical data in R?
> 
> Specifically, I have an array, say with 1000 entries, where each entry  
> is a string of 4 characters (in any order, 24 possibilities in my  
> case). I would like on the y-axis all the strings that are in the  
> array as labels. The x-axis I would like labeled 0 to 1000. The line  
> is to show how the strings change as we move through the array.
> 
> (This is essentially a trace plot of a Markov Chain Monte Carlo  
> algorithm. I think essentially I would like an equivalent to  
> plot(myArray, type='l') but with discrete, finite, non-numerical  
> values on the y-axis)
> 
> Is this possible?
> 
> Michal.

For some pre-existing possibilities, you might want to look at the
following CRAN packages:

MCMCPack
mcmc
coda
scapeMCMC

Alternatively, consider coercing your character values to a factor,
predicated upon some relevant ordering.  You can then plot the numeric
values of the factors for your y axis. 

Simple example:

Y <- sample(LETTERS, 1000, replace = TRUE)

plot(1:1000, factor(Y), type = "l", yaxt = "n")

axis(2, at = 1:26, labels = LETTERS, cex.axis = 0.75)


HTH,

Marc Schwartz