R help - May 2010 - Transforming sequence data into numeric values.

Hi I am analysing from a behavioural experiment comparing left and right
turns of snails.

Basically I end up with a list of twenty values like this:

R
R
R
L
R
L
L
L
L
R
R
R
R
L
L
L
R
L
R
L

I want to analyse runs of turns but would like to automate how this is
processed and end up with a table that displays the frequency of the
sequences (L, LL, LLL, R, RR, RRR etc).

Is it possible to construct something like this using R and how would I go
about doing it?

Thanks

Simon Boardman

	[[alternative HTML version deleted]]

Here is one possibility:

tmp <- sample(c('R','L'), 100, replace=TRUE)
tmp2 <- rle(tmp)
tmp3 <- sapply( 1:length(tmp2$values), 
  function(i) paste( rep(tmp2$values[i], tmp2$lengths[i]), collapse='')
)
table(tmp3)

the rle function computes the run lengths, the sapply line converts those
results into things like "LLL", then table just counts them up.

Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Simon Boardman
> Sent: Friday, May 07, 2010 4:30 AM
> To: r-help at r-project.org
> Subject: [R] Transforming sequence data into numeric values.
> 
> Hi I am analysing from a behavioural experiment comparing left and
> right
> turns of snails.
> 
> Basically I end up with a list of twenty values like this:
> 
> R
> R
> R
> L
> R
> L
> L
> L
> L
> R
> R
> R
> R
> L
> L
> L
> R
> L
> R
> L
> 
> I want to analyse runs of turns but would like to automate how this is
> processed and end up with a table that displays the frequency of the
> sequences (L, LL, LLL, R, RR, RRR etc).
> 
> Is it possible to construct something like this using R and how would I
> go
> about doing it?
> 
> Thanks
> 
> Simon Boardman
> 
> 	[[alternative HTML version deleted]]
> 
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