[R] counting strings of identical values in a matrix

[A M Lavezzi]

Hello

I have this problem. I have a large matrix of this sort:

 > prova
      [,1] [,2] [,3] [,4]
[1,]    3    3    3    3
[2,]    3    3    3    1
[3,]    1    3    3    3
[4,]    1    1    1    3
[5,]    3    1    1    3
[6,]    3    1    1    3
[7,]    1    3    1    3
[8,]    1    3    3    3

What I want to do is to count the number of 
sequences of ones and stack the results in a 
vector, which I will subsequently use to build an istogram (or a density)

I mean: in the matrix "prova" I have two 
sequences of length two in column 1, one sequence 
of length three in column 2, one sequence  of 
length four in column 3 and one sequence of 
length one in column 4. (I know I can actually 
turn the matrix into a vector by using rep(prova))

I would like to get to a vector such as : xx = [1,2,1,1]

Can anyone help?

Thanks!

Mario


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Andrea Mario Lavezzi
Dipartimento di Studi su Politica Diritto e Società
Piazza Bologni 8
90134 Palermo
tel. ++39 091 6625600
fax ++39 091 6112023
skype: lavezzimario
email: lavezzi at unipa.it
web: http://www.unipa.it/~lavezzi
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