From ggrothendieck @ending from gm@il@com  Mon Jul 30 16:04:27 2018
From: ggrothendieck @ending from gm@il@com (Gabor Grothendieck)
Date: Mon, 30 Jul 2018 10:04:27 -0400
Subject: [Rd] apply with zero-row matrix
In-Reply-To: <CAARY7kjL=buR9GE9rP8Y64D_WTdrFunfTMUXD2mw8P4gMsNrTQ@mail.gmail.com>
References: <CAARY7khVXzxutThhKcq+ZftTE8-66eH-B-82xs-8TFyTTmGrkw@mail.gmail.com>
 <CAARY7kjL=buR9GE9rP8Y64D_WTdrFunfTMUXD2mw8P4gMsNrTQ@mail.gmail.com>
Message-ID: <CAP01uRkYM7CMZ2eJGLQmeybdAnsV9AGDtwROMnGB2toukG15SQ@mail.gmail.com>

Try pmap and related functions in purrr:

  pmap(as.data.frame(m), ~ { cat("Called...\n"); print(c(...)) })
  ## list()

On Mon, Jul 30, 2018 at 12:33 AM, David Hugh-Jones
<davidhughjones at gmail.com> wrote:
> Forgive me if this has been asked many times before, but I couldn't find
> anything on the mailing lists.
>
> I'd expect apply(m, 1, foo) not to call `foo` if m is a matrix with zero
> rows.
> In fact:
>
> m <- matrix(NA, 0, 5)
> apply(m, 1, function (x) {cat("Called...\n"); print(x)})
> ## Called...
> ## [1] FALSE FALSE FALSE FALSE FALSE
>
> Similarly for apply(m, 2,...) if m has no columns.
> Is there a reason for this? Could it be documented?
>
> David
> --
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>
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[Rd] apply with zero-row matrix
Gabor Grothendieck