# Rajarshi Guha <rajarshi@presidency.com>
# 8/12/2004

nbr.behavior <- function(act, desc, dist=FALSE, do.plot=TRUE, ...) {

    if (length(act) != nrow(desc)) {
        stop('Length of activity vector and rows of descriptor matrix must match')
    }
    if (!is.matrix(desc) && !is.data.frame(desc)) {
        stop('desc should be a matrix or data.frame')
    }

    x <- numeric(length(act)*(length(act)-1)/2)
    y <- numeric(length(act)*(length(act)-1)/2)
    cnt <- 1

    # see if we were supplied a distance matrix
    if (!dist) {
        dm <- as.matrix(dist(desc))
    } else {
        dm <- desc
    }

    for (i in 1:(length(act)-1)) {
        for (j in (i+1):length(act)) {
            x[cnt] <- dm[i,j]
            y[cnt] <- abs(act[i] - act[j])
            cnt <- cnt + 1
        }
    }

    if (do.plot) {
        par(pty='s',pch=19,col='black')
        plot(x,y, xlab='Pairwise Distance\'s', ylab='Absolute Difference in Activity', ...)
    }
    list(x=x,y=y)
}