Number of different states/events in a sequence with TraMineR

Question

I'm interested in counting the number of different states present in each sequence of my dataset. For sake of simplicity, I'll use a TraMineR example:

1. starting from this sequence:

   1230 D-D-D-D-A-A-A-A-A-A-A-D

2. then computing the extract distinct states with the seqdss function obtaining:

   1230 D-A-D

Is there a function to extract the overall number of different states in the sequence only accounting for presence of a state and not its potential repetition along the sequence? In other words, for the case described above I would like to obtain a vector containing for this sequence the value 2 (event A and event D) instead of 3 (1 event A + 2 events D).
Thank you.

Answer 1

You can compute the number of distinct states by first computing the state distribution of each sequence using seqistatd and then summing the number of non-zero elements in each row of the matrix returned by seqistatd. I illustrate below using the biofam data:

library(TraMineR)
data(biofam)
bf.seq <- seqdef(biofam[,10:25])

## longitudinal distributions 
bf.ldist <- seqistatd(bf.seq)
n.states <- apply(bf.ldist,1,function(x) sum(x != 0))

## displaying results
bf.ldist[1:3,]
     0  1 2 3 4 5 6 7
1167 9  0 0 1 0 0 6 0
514  1 10 0 1 0 0 4 0
1013 7  5 0 1 0 0 3 0

n.states[1:3]
1167  514 1013 
   3    4    4 

Answer 2

I might be missing something here, but it looks like you're after unique.

Answer 3

Your expected result is not clear ( maybe because you describe it in English and not in pseudo code). I guess you you are looking for table to count number of states per subject. Here I am using provided with TraMineR package:

library(TraMineR)
data(actcal)
actcal.seq <- seqdef(actcal,13:24)
head(actcal.seq )

     Sequence               
2848 B-B-B-B-B-B-B-B-B-B-B-B
1230 D-D-D-D-A-A-A-A-A-A-A-D
2468 B-B-B-B-B-B-B-B-B-B-B-B
654  C-C-C-C-C-C-C-C-C-B-B-B
6946 A-A-A-A-A-A-A-A-A-A-A-A
1872 D-B-B-B-B-B-B-B-B-B-B-B

Now applying table to the 4th row for example:

tab <- table(unlist(actcal.seq[4,]))
tab[tab>0]
B C 
3 9