R/is.sd.r

In adehabitat: Analysis of Habitat Selection by Animals

is.sd <- function(ltraj)
{
    if (!inherits(ltraj,"ltraj"))
        stop("ltraj should be of class \"ltraj\"")
    if (!is.regular(ltraj))
        stop("ltraj should be regular")
    len <- unlist(lapply(ltraj, length))
    len <- all(len==len[1])
    return(len)
}

sd2df <- function(ltraj, what)
{
    if (!inherits(ltraj,"ltraj"))
        stop("ltraj should be of class \"ltraj\"")
    if (!is.sd(ltraj))
        stop("ltraj should contain regular bursts (same time lag), with the same duration")

    res <- lapply(ltraj, function(x) x[what])
    res <- do.call("data.frame",res)
    names(res) <- burst(ltraj)
    return(res)
}