R/slopeDist.R

In tscR: A time series clustering package combining slope and Frechet distances

#' Pairwise slope distance
#'
#' Compute pairwise distance based on slopes in a matrix of trajectories
#'
#'
#' @param x Numeric matrix or data.frame with trajectory values. Rows are
#'  trajectories, columns are time or similar. SummarizedExperiment
#'  object can be provided for compatibility with bioconductor container (for
#'  more information see vignette).
#' @param time Numeric vector with time data (time intervals), with equal
#'  length to columns number in x.
#' @param ... Other arguments to pass to importFromSE if _x_
#' is SummarizedExperiment-class.
#'
#' @return A dist class object of size NxN, where N is rows number
#'  in the input data
#'
#'
#' @examples
#'
#' data(tscR)
#' data <- tscR
#' time <- c(1,2,3)
#' dist_tscR <- slopeDist(data, time)
#'
#'
#' @seealso \code{\link{frechetDistC} and \link{frechetDist} (R and slower
#'  versión than frechetDistC.), \link{importFromSE}.}
#'
#' @author  Fernando Pérez-Sanz (\email{fernando.perez8@@um.es})
#' @author  Miriam Riquelme Pérez (\email{miriam.riquelmep@@gmail.com})


slopeDist <- function(x, time, ...) {
    if(is(x, "SummarizedExperiment")){
        x <- importFromSE(x, ...)
    }
    if (dim(x)[1] > 1000) {
        warning(
            "Large matrix or data.frame could cause memory problems.
            You should use imputeSenators function"
        )
    }
    if (is.data.frame(x)) {
        x <- as.matrix(x)
    }
    if (!is.matrix(x)) {
        stop("X must be matrix or data.frame")
    }
    if (length(time) != dim(x)[2]) {
        stop("Time vector must be the same length as x rows")
    }
    N <- dim(x)[1]
    M <- dim(x)[2]
    m1 <- x[,-c(M)]
    m2 <- x[,-c(1)]
    mdif <- m2 - m1
    voptimizado <- mdif %*% diag(1 / (time[2:M] - time[seq_len(M -
                                                                   1)]))
    mydist <- dist(voptimizado,
                   method = "euclidean",
                   diag = TRUE,
                   upper = TRUE)
    return(mydist)
}