R/oneBkp.R

In jointseg: Joint segmentation of multivariate (copy number) signals

oneBkp <- structure(function(#Get best candidate change point
### Get best candidate change point according to binary segmentation
                             Y,
### A \code{n*p} matrix, \code{p} signals of length \code{n} to be
### segmented (centered by column)
                             weights=NULL,
### a \code{(n-1)*1} vector of weights for the candidate change point
### positions. Default weights yield the likelihood ratio test (LRT)
### statistic for the identification of a single change point.
                             verbose=FALSE
### A \code{logical} value: should extra information be output ? Defaults to \code{FALSE}.
                             ){
    ##keyword<<internal
    
    ## Initialization
    if (!is.matrix(Y)){
        stop("Y is not a matrix, please check dimension of Y")
    }
    p <- dim(Y)[2]
    n <- as.numeric(nrow(Y))
    if (is.null(weights)) {
        weights=defaultWeights(n)
    } 

    c <- leftMultiplyByXt(Y=Y, w=weights, verbose=verbose)
    if (is.null(dim(c))) str(c)
    cNorm <- rowSums(c^2)
    which.max(cNorm)
}, ex=function(){
    p <- 2
    sim <- randomProfile(1e4, 1, 1, p)
    Y <- sim$profile
    bkp <- jointseg:::oneBkp(Y)
    par(mfrow=c(p,1))
    for (ii in 1:p) {
        plot(Y[, ii], pch=19, cex=0.2)
        abline(v=bkp, col=3)
        abline(v=sim$bkp, col=8, lty=2)
    }
})

############################################################################
## HISTORY:
## 2013-01-30
## o Now an internal function (not exported anymore).
## o Added 'jointSeg:::' to example because function is not exported anymore.
## 2013-01-09
## o Replaced 'jump' by 'bkp'.
## 2012-12-27
## o Some code and doc cleanups.
## 2012-12-05
## o Created.
############################################################################