On 03/31/2017 10:14 PM, Prof Brian Ripley wrote:
From ?NA
Numerical computations using ‘NA’ will normally result in ‘NA’: a
possible exception is where ‘NaN’ is also involved, in which case
either might result.
and ?NaN
Computations involving ‘NaN’ will return ‘NaN’ or perhaps ‘NA’:
which of those two is not guaranteed and may depend on the R
platform (since compilers may re-order computations).
fortunes::fortune(14) applies (yet again).
The problem is that TFM often contradicts itself e.g. in ?prod:
If ‘na.rm’ is ‘FALSE’ an ‘NA’ value in any of the arguments will
cause a value of ‘NA’ to be returned, otherwise ‘NA’ values are
ignored.
which is clearly not the case (at least for me):
> x <- c(NaN, NA)
> prod(x)
[1] NaN
H.
On 01/04/2017 04:50, Henrik Bengtsson wrote:
In R 3.3.3, I observe the following on Ubuntu 16.04 (when building
from source as well as for the sudo apt r-base build):
x <- c(NA, NaN)
mean(x)
[1] NA
mean(rev(x))
[1] NaN
rowMeans(matrix(x, nrow = 1, ncol = 2))
[1] NA
rowMeans(matrix(rev(x), nrow = 1, ncol = 2))
[1] NaN
.rowMeans(x, m = 1, n = 2)
[1] NA
.rowMeans(rev(x), m = 1, n = 2)
[1] NaN
.rowSums(x, m = 1, n = 2)
[1] NA
.rowSums(rev(x), m = 1, n = 2)
[1] NaN
rowSums(matrix(x, nrow = 1, ncol = 2))
[1] NA
rowSums(matrix(rev(x), nrow = 1, ncol = 2))
[1] NaN
I'd expect NA to trump NaN in all cases (with na.rm = FALSE). sum()
does not have this problem and returns NA in both cases (*).
For the same R version build from source on RHEL 6.6 system
(completely different architecture), I get the expected result (= NA)
for all of the above cases, e.g.
x <- c(NA, NaN)
mean(x)
[1] NA
mean(rev(x))
[1] NA
[...]
Before going insane trying to troubleshoot this, I have a vague memory
that this, or something related to this, has been discussed
previously, but I cannot locate it.
Is the above a bug in R, a FAQ, a build error, overzealous compiler
optimization, and / or ...?
Thanks,
Henrik
--
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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