[R] How can make loop more faster?

[Fabrice Tourre]

Dear expert,

How can I make follow codematrix function more faster?

top20.dat <- top20.dat[,7:length(top20.dat[1,])]
top40.dat <-
read.table("top40snps.ped",header=F,sep="\t",stringsAsFactors=F)
row.names(top40.dat) <- top40.dat[,1]
top40.dat <- top40.dat[,7:length(top40.dat[1,])]
codematrix <- function(dat)
{
    new.dat <- dat
    for(col in 1:length(dat[1,]))
    {
        tbl <- table(dat[,col])
        max.allel <- names(which(tbl==max(table(dat[,col]))))
        for(row in 1:length(dat[,1]))
            {
                if(dat[row,col]=="0 0")
                {
                    new.dat[row,col]=NA
                }else{
                    if(dat[row,col]==max.allel) {
                        new.dat[row,col]=0
                    }else{
                        allele <- unlist(strsplit(
as.character(dat[row,col])," "))
                        if(allele[1]==allele[2]){
                            new.dat[row,col]=2
                        }else{
                            new.dat[row,col]=1
                        }
                    }
                }
            }
        #})
        cat(paste(col," ",sep=""))
    }
    return(new.dat)
}
code.top20 <- codematrix(top20.dat)

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