R help - Mar 2009 - frequency of subsequent events

Hello,
The example shows a sequence of songtypes a bird has sang.
The entire list contains several thousand songs which the bird has produced
consecutively.
Is there any convenient way in R to produce a contingency table which shows how
often a special song type was sang after a special other songtype? Or within a
determined frame of e.g. 10 consecutively produced songs?

Example:

Nr	Songtype
1	S1
2	S2
3	S3
4	S1
5	S1
6	S2
7	S4

Contingency table:

S1	S2	S3	S4 subsequent songs
S1	1	2	0	0
S2	0	0	1	1
S3	1	0	0	0
S4	0	0	0	0
Preceding  
Songs


Greetings
Michael 









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?lag
?xtabs

songseq <- read.table(textConnection("Nr	Songtype
  1	S1
  2	S2
  3	S3
  4	S1
  5	S1
  6	S2
  7	S4"), header=TRUE, stringsAsFactors=FALSE)

  songseq$precsong <-c(NA,lag(songseq$Songtype)[1:6])
# need to drop last entry

  xtabs( ~ precsong + Songtype, data=songseq)
         Songtype
precsong S1 S2 S3 S4
       S1  1  2  0  0
       S2  0  0  1  1
       S3  1  0  0  0

#may want to set extra levels if S4 song type does not have a subsequent
--  
David Winsemius, MD
Heritage Laboratories
West Hartford, CT


On Mar 6, 2009, at 3:14 PM, miweiss1 at freenet.de wrote:
> Hello,
> The example shows a sequence of songtypes a bird has sang.
> The entire list contains several thousand songs which the bird has  
> produced consecutively.
> Is there any convenient way in R to produce a contingency table  
> which shows how often a special song type was sang after a special  
> other songtype? Or within a determined frame of e.g. 10  
> consecutively produced songs?
>
> Example:
>
> Nr	Songtype
> 1	S1
> 2	S2
> 3	S3
> 4	S1
> 5	S1
> 6	S2
> 7	S4
>
> Contingency table:
>
> S1	S2	S3	S4 subsequent songs
> S1	1	2	0	0
> S2	0	0	1	1
> S3	1	0	0	0
> S4	0	0	0	0
> Preceding
> Songs
>
>
> Greetings
> Michael