Hello,
I have the following problem.
I am running simulations on possible states of a set of agents
(1=employed, 0=unemployed).
I store these simulated time series in a matrix like the following,
where rows indicates time periods, columns the number of agents (4
agents and 8 periods in this case):
Atr=[
1 1 1 1
1 1 0 1
1 1 0 1
1 1 0 1
0 1 0 1
0 1 0 1
0 1 0 1
0 1 0 1]
At this point, I need to update a vector ("unSpells") which contains the
lenghts of unemployment spells, and is initialized with ones.
Practically, in the case represented I need to store the value "4" at
position 1 of unSpells and "7" at position 3 of unSpells (that is, I
care only of those who, in the last row, are zeros).
I am doing this in the following way (tt+1 indicates the time period
reached by the simulation, n the number of agents):
unSpells = matrix(1,nrow=1,ncol=n)
ppp=apply(Atr[1:(tt+1),],2,rle)
for(i in (1:n)[Atr[tt+1,]==0]){
unSpells[i]=tail(ppp[[i]]$lengths,1)
}
It works, but the for (i in ...) loop slows down the simulation a lot.
Any suggestion on how to avoid this loop? (or in general, to speed up
this part of the simulation)
Thanks!!
Mario
--
Andrea Mario Lavezzi
Dipartimento di Studi su Politica, Diritto e Società
Università di Palermo
Piazza Bologni 8
90134 Palermo, Italy
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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