[R] Multi-dimensional function.

"José Luis Aznarte M." jlaznarte at decsai.ugr.es
Fri Jan 4 20:08:37 CET 2008


    Hi there! Happy new year to everyone!
    There's a piece of code that I must write that's driving me crazy. 
Maybe any of you has previous experiences in something similar. Any help 
will be greatly appreciated!

    The problem is as follows. I have a matrix Z with dimensions c(m, 
p). I have two vectors
Gamma and Th with length p.
    What I want to do is, for j in 1:p, for each pair (Gamma[j], Th[j]), 
apply the logistic function to each column of z, using plogis(Z[,j], 
Th[j], 1/Gamma[j]). Then, by concatenating the result of each iteration 
I would obtain a matrix lZ with dimensions c(m, p).

    Now, the question is: is there a neat way to do this in a single 
step, i.e., without the obvious loop? I have a not-so-good relationship 
with the "apply" family, but I suspect there should be a way. Sorry if 
this is a silly question...
    Thanks and best wishes for the new year to you all! Salud!




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