[R] transitions in R

[Jonathan Baron]

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>Subject: [R] transitions in R
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>Hi, All.  I'd have a set of data in an array:
>
>process <- c( 5 , 7 , 4 , 1 , 4 , 1 , 4 , 1 , 4 , 4 , 1 , 5 , 4 , ...)
>
>and I'd like to know the number of transitions in this data.  I
>calculate transitions as the number of times a number follows another
>number.  thus, something like this would be a 1 deep transition:
>
>1 --> 1 : 10% (and actual number of 1 --> 1 occurrences)
>1 --> 2 : 2%
>1 --> 3 : 23%
>...
>2 --> 1 : 2%
>2 --> 2 : 8%
>(etc.)
>
>of course, you can have 2 or 3 or n deep transitions, but I'm really
>only interested in 1 and 2 (and maybe 3) deep transitions.
>
>what is the best way of calculating this info in R?

For the one-deep try
plength <- length(process)
table(process[1:(plength-1)],process[2:plength])

To get proportions,
table(process[1:(plength-1)],process[2:plength])/(plength-1)

Multiply by 100 to get percent, and use round() if needed.

I think you can extend this to more depth and get bigger tables.

Jon Baron
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