[Rd] suggestion for subset.data.frame()

From: Benjamin Tyner <btyner_at_gmail.com>
Date: Wed, 22 Jun 2011 21:55:04 -0400


Hello,

Currently, subset.data.frame() does

    if (missing(subset))

            r <- TRUE
        else {

perhaps better might be:

    if (missing(subset))

            r <- rep(TRUE, nrow(x))
        else {

The rationale being, if 'x' has zero rows and 'subset' is missing, we don't want to end up with more rows than we started with:

> subset(head(iris, 0), select = -Species)

       Sepal.Length Sepal.Width Petal.Length Petal.Width
    NA           NA          NA           NA          NA

Thoughts?
-Ben



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