[R] Analyzing large transition matrix

[Jim Lemon]

On 06/23/2010 11:30 PM, Bill Harris wrote:
> Let's say you have a dataframe of car trade-ins.  For example, each row
> contains
>
> oldcar   newcar   qty
>
> and a typical entry could be
>
> lexus   bmw    1
>
> I put the qty column to allow for fleet purchases, where one purchase
> may convert multiple cars at once.
>
> I'd like to show what's going on.  I could do a histogram of newcar to
> show the frequency each type of car is bought.  If there are 5-10 car
> types, that works.  If there are 50-100 or more, the legend gets
> illegible.
>
> I could also do a histogram of oldcar to see what people gave up, but
> that's less interesting.
>
> I'm considering a correlogram using the corrgram package, but a heat map
> might work, too.  Any tips on making the legends useful in any of this?
> Any better approaches to try?
>
> I tried table() and prop.table() to see if I could get transition
> probabilities as if this were a Markov chain, but dim() comes out 108
> 78, which is still too big to print or visualize.
>
Hi Bill,
You could use sizetree (plotrix) if you have one car per line, but with 
50-100 initial categories, you're going to need a long piece of paper.

Jim