On 2010-04-26 20:05, Matthew Keller wrote:
Rolf: "Well then, why don't you go away and design and build your own
statistics and data analysis language/package to replace R?"
What a nice reply! The fellow is just trying to understand R. That
response reminds me of citizens of my own country who cannot abide by
any criticism of the USA: "If you don't like it, why don't you leave?"
Classy.
Let's not take things too far out of context. Rolf was replying
to someone who was 'very annoyed' that R has the concept of a
vector. That poster felt that, since a vector is just a special
case of a matrix, there was no need for the vector concept. That
poster had also not yet read enough to realize that there *is*
the 'drop=FALSE' argument.
It's a bit strong to complain that R was not designed to suit
your own needs and yours alone, never mind what others might
think.
I have found R-core to be quite receptive to intelligent and
well thought-out suggestions. But "It is very annoying!" is
not the right approach.
-Peter Ehlers
I have sympathies with the author. When I first began using R
(migrating from Matlab), I also found the vector concept strange,
especially because I was doing a lot of matrix algebra back then and
didn't like the concept of conflating a row vector with a column
vector. But I've since gotten used to it and can hardly remember why I
struggled with this early on. Perhaps your experience will be similar.
Best of luck!
Matt
On Mon, Apr 26, 2010 at 7:40 PM, Charles C. Berry<cbe...@tajo.ucsd.edu> wrote:
On Mon, 26 Apr 2010, Stu wrote:
Hi all,
One subtlety is that the drop argument only works if you specify 2 or
more indices e.g. [i, j, ..., drop=F]; but not for a single index e.g
[i, drop=F].
Wrong.
a<- structure(1:5,dim=5)
dim(a)
[1] 5
dim(a[2:3,drop=F]) # don't drop regardless
[1] 2
dim(a[2,drop=F]) # dont' drop regardless
[1] 1
dim(a[2:3,drop=T]) # no extent of length 1
[1] 2
dim(a[2,drop=T]) # drop, extent of length 1
NULL
Why doesn't R complain about the unused "drop=F" argument in the
single index case?
In the example you give (one index for a two-dimension array), vector
indexing is assumed. For vector indexing, drop is irrelevant.
HTH,
Chuck
Cheers,
- Stu
a = matrix(1:10, nrow=1)
b = matrix(10:1, ncol=1)
# a1 is an vector w/o dim attribute (i.e. drop=F is ignored silently)
(a1 = a[2:5, drop=F])
dim(a1)
# a2 is an vector WITH dim attribute: a row matrix (drop=F works)
(a2 = a[, 2:5, drop=F])
dim(a2)
# b1 is an vector w/o dim attribute (i.e. drop=F is ignored silently)
(b1 = b[2:5, drop=F])
dim(b1)
# b2 is an vector WITH dim attribute: a column matrix (drop=F works)
(b2 = b[2:5, , drop=F])
dim(b2)
On Mar 30, 4:08Â pm, lith<minil...@gmail.com> wrote:
Reframe the problem. Rethink why you need to keep dimensions. I never
ever had to use drop.
The problem is that the type of the return value changes if you happen
to forget to use drop = FALSE, which can easily turn into a nightmare:
m<-matrix(1:20, ncol=4)
for (i in seq(3, 1, -1)) {
  print(class(m[1:i, ]))}
[1] "matrix"
[1] "matrix"
[1] "integer"
______________________________________________
r-h...@r-project.org mailing
listhttps://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting
guidehttp://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Charles C. Berry               (858) 534-2098
                      Dept of
Family/Preventive
Medicine
E mailto:cbe...@tajo.ucsd.edu        UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ Â La Jolla, San Diego 92093-0901
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
Peter Ehlers
University of Calgary
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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