[Rd] stats::screeplot suggestion

[Michael Friendly]

  Hi

Here is a suggestion/request for stats::screeplot

* Please allow to change xlab and ylab.  The attached file does that, and maintains current behavior. Reason: strictly speaking, ylab should be "Variance" (singular). It would also be better to have an explicit label for the X axis: "Component"

In the would-be-nice-if category, I suggest addition of a type="cumulative" chart, a line graph of cumulative % of variance, labeled "% Variance" by default.

-Michael

----- screeplot.default.R ---------

screeplot.default <- function (x, npcs = min(10, length(x$sdev)),
                type = c("barplot", "lines"),
                xlab = "",
                ylab = "Variances",
                main = deparse(substitute(x)), ...)
{
     main
     type <- match.arg(type)
     pcs <- x$sdev^2
     xp <- seq_len(npcs)
     dev.hold()
     on.exit(dev.flush())
     if (type == "barplot")
         barplot(pcs[xp], names.arg = names(pcs[xp]), main = main,
             ylab = ylab, ...)
     else {
         plot(xp, pcs[xp], type = "b", axes = FALSE, main = main,
             xlab = xlab, ylab = ylab, ...)
         axis(2)
         axis(1, at = xp, labels = names(pcs[xp]))
     }
     invisible()
}

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-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept. & Chair, ASA Statistical Graphics Section
York University      Voice: 416 736-2100 x66249 Fax: 416 736-5814
4700 Keele Street    Web:   http://www.datavis.ca  |  @datavisFriendly
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