# File:   colMatches.r

colMatchesHelp = function()
{
    cat("# --------------------------------------------------\n")
    cat("Syntax: colMatches(A,szmatch)\n")
    cat("For each column in array A checks if at least one entry is\n")
    cat("repeated n times\n")
    cat("\n")
    cat("A = array\n")
    cat("szmatch = the number of matches \n")
    cat("\n")
    cat("Returns a vector of 0's and 1's: 1 means at least\n")
    cat("one entry was repeated at least szmatch times.\n")
    cat("# --------------------------------------------------\n")

}
colMatches = function(A,szmatch=2)
{
    # See colMatchesHelp()
    
    #RED_FLAG: We assume A is a vector or 2 dimensional array
    #RED_FLAG: We don't check that szmatch > 0
    A.dim=dim(A)
    if (is.null(A.dim))
    {
        #assume A is a column vector
        nrows = length(A)
        ncols = 1
        Asrt= matrix(sort(A),nrow=nrows,ncol=ncols)
    }
    else
    {
        nrows=A.dim[1]
        ncols = A.dim[2]
        #apply() is an r-magic function. In this case it applies sort to each column. To apply to each row use apply(A,1,sort)
        Asrt = apply(A,2,sort)
    }
    if (szmatch > nrows)
    {
        #Can't possibly have more matches than rows, return a vector of 0's
        b = rep(0,times=ncols) 
    }
    else
    {
        #Sneaky way to look for runs of szmatch in sorted columns
        x= Asrt[szmatch:nrows,] == Asrt[1:(nrows-szmatch+1),]
        if (ncols == 1)
            b = 1.*(sum(x) > 0)
        else if (szmatch == nrows)
            b=as.vector(1.*x)
        else
            b=as.vector(1.*(apply(x,2,sum) >0))
    }
    return(b)
}