On 06/08/2018 02:15 PM, Hadley Wickham wrote:
On Fri, Jun 8, 2018 at 2:09 PM, Berry, Charles <ccbe...@ucsd.edu> wrote:
On Jun 8, 2018, at 1:49 PM, Hadley Wickham <h.wick...@gmail.com> wrote:
Hmmm, yes, there must be some special case in the C code to avoid
recycling a length-1 logical vector:
Here is a version that (I think) handles Herve's issue of arrays having one or
more 0 dimensions.
subset_ROW <-
function(x,i)
{
dims <- dim(x)
index_list <- which(dims[-1] != 0L) + 3
mc <- quote(x[i])
nd <- max(1L, length(dims))
mc[ index_list ] <- list(TRUE)
mc[[ nd + 3L ]] <- FALSE
names( mc )[ nd+3L ] <- "drop"
eval(mc)
}
Curiously enough the timing is *much* better for this implementation than for
the first version I sent.
Constructing a version of `mc' that looks like `x[i,,,,drop=FALSE]' can be done
with `alist(a=)' in place of `list(TRUE)' in the earlier version but seems to
slow things down noticeably. It requires almost twice (!!) as much time as the
version above.
I think that's probably because alist() is a slow way to generate a
missing symbol:
bench::mark(
alist(x = ),
list(x = quote(expr = )),
check = FALSE
)[1:5]
#> # A tibble: 2 x 5
#> expression min mean median max
#> <chr> <bch:tm> <bch:tm> <bch:tm> <bch:tm>
#> 1 alist(x = ) 2.8µs 3.54µs 3.29µs 34.9µs
#> 2 list(x = quote(expr = )) 169ns 219.38ns 181ns 24.2µs
(note the units)
That's a good one. Need to change this in S4Vectors::default_extractROWS()
and other places. Thanks!
H.
Hadley
--
Hervé Pagès
Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024
E-mail: hpa...@fredhutch.org
Phone: (206) 667-5791
Fax: (206) 667-1319
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