Hello list,
I have found a weird behavior of the aggregate() function when used with
characters. I think the problem as to do with converting characters to factors.
I'm trying to aggregate a character vector using an homemade function. My
function is giving me all the possible pairs of modalities observed.
Reproducible code:
#######
### my grouping variable
gr <- c("A","A","B","B","C","C","C","D","D","E","E","E")
### my variable
vari <-
c("rs2","rs2","mj2","mj1","rs1","rs1","rs2","mj1","mj1","rs1","mj1","mj2")
### what the table would look like
cbind(gr,vari)
### My function that gives every pairs of variables possible (my real function
can go up to length(TE)==5, but for the sake of the example, I've reduced it
here)
faire.paires <- function(TE){
gg <- rbind(c(TE[1],TE[2]),
c(TE[1],TE[3]))
gg <- gg[rowSums(is.na(gg))==0,,drop=F]
gg
}
### The function gives exactly what I want when I run it on a specific entry
faire.paires(TE = vari[gr=="B"])
### But with aggregate(), it transforms everything into integer
res <- aggregate(list(TE = vari), by=list(gr),faire.paires)
res
str(res)
### it's like it's using factor than losing the key to tell me which integer
### mean which modality
### if I give it directly factors:
res2 <- aggregate(list(TE = as.factor(vari)), by=list(gr),faire.paires)
res2
str(res2)
### does not fix the problem.
############
Any idea?
I know my function may not be the best or most efficient way to succeed.
However, I'm still puzzled on
why aggregate gives me this weird output.
Best regards,
Bastien Ferland-Raymond, M.Sc. Stat., M.Sc. Biol.
Division des orientations et projets spéciaux
Direction des inventaires forestiers
Ministère des Forêts, de la Faune et des Parcs
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