R/phases.R

In onemap: Construction of Genetic Maps in Experimental Crosses

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# Package: onemap                                                     #
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# File: phases.R                                                      #
# Contains: phases                                                    #
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# Written by Marcelo Mollinari                                        #
# copyright (c) 2009, Marcelo Mollinari                               #
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# First version: 02/27/2009                                           #
# License: GNU General Public License version 2 (June, 1991) or later #
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# This function gathers information from two-point analyses and makes
# a list with plausible linkage phases, with the respective
# recombination fractions
phases <- function(input.seq, LOD=0, max.rf=0.50)
{
    ## checking for correct object
    if(!inherits(input.seq,"sequence")) stop(deparse(substitute(input.seq))," is not an object of class 'sequence'")
    
    tot <- choose(length(input.seq$seq.num),2)
    ## initial values for the recombination fraction
    rf.init <- vector("list",tot)
    ## initially relevant linkage phases
    phase.init <- vector("list",tot)
    
    temp <- matrix(NA,4,2)
    
    for (i in 2:length(input.seq$seq.num)) {
        for (j in 1:(i-1)) {
            ## recover values from two-point analyses
            big <- pmax.int(input.seq$seq.num[i],input.seq$seq.num[j])
            small <- pmin.int(input.seq$seq.num[i],input.seq$seq.num[j])
            temp <- t(sapply(input.seq$twopt$analysis, function(x,i,j) cbind(x[j,i], x[i,j]), small, big))
            
            ## check which assignments meet the criteria
            relevant <- which(temp[,2]>(max(temp[,2])-0.005)) ## maximum LOD scores
            phase.init[[acum(i-2)+j]] <- relevant[which((temp[relevant,1] <= max.rf & temp[relevant,2] >= LOD))]
            if (length(phase.init[[acum(i-2)+j]]) == 0) phase.init[[acum(i-2)+j]] <- 1:4
            rf.init[[acum(i-2)+j]] <- temp[phase.init[[acum(i-2)+j]],1]
        }
    }   
    list(phase.init=phase.init, rf.init=rf.init)
}

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