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#  File src/library/base/R/jitter.R
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### Unimplemented Idea {for amount = NULL ?}
### Really "optimal" (e.g. for rug()), use a non-constant amount,
### e.g. use "d" = diff(xx)  BEFORE  taking min()...

jitter <- function(x, factor = 1, amount=NULL)
{
    if(length(x) == 0L)
    return(x)
    if(!is.numeric(x))
        stop("'x' must be numeric")
    z <- diff(r <- range(xf <- x[is.finite(x)]))
    if(z == 0) z <- abs(r[1L])
    if(z == 0) z <- 1

    if(is.null(amount)) {       # default: Find 'necessary' amount
    d <- diff(xx <- unique(sort.int(round(xf, 3 - floor(log10(z))))))
    d <- if(length(d)) min(d) else if(xx != 0) xx/10 else z/10
    amount <- factor/5 * abs(d)
    } else if(amount == 0)      # only then: S compatibility
    amount <- factor * (z/50)

    x + amount * stats::runif(length(x), -1, 1)
}