Displaying 20 results from an estimated 8000 matches similar to: "Light-weight data.frame class: was: how to add method to .Primitive function"
2005 May 04
1
Cost of method dispatching: was: when can we expect Prof Tierney's compiled R?
> -----Original Message-----
> From: Prof Brian Ripley [mailto:ripley@stats.ox.ac.uk]
> Sent: Wednesday, April 27, 2005 1:13 AM
> To: Vadim Ogranovich
> Cc: Luke Tierney; r-devel@stat.math.ethz.ch
> Subject: Re: [Rd] RE: [R] when can we expect Prof Tierney's
> compiled R?
>
> On Tue, 26 Apr 2005, Vadim Ogranovich wrote:
>
...
> > The arithmetic shows
2005 Apr 27
1
RE: [R] when can we expect Prof Tierney's compiled R?
Luke,
Thank you for sharing the benchmark results. The improvement is very
substantial, I am looking forward to the release of the byte compiler!
The arithmetic shows that x[i]<- is still the bottleneck. I suspect that
this is due to a very involved dispatching/search for the appropriate
function on the C level. There might be significant gain if loops
somehow cached the result of the initial
2005 May 07
4
how to add method to .Primitive function
Hi,
I tried to write the dim method for the list class, but R doesn't seem
to dispatch to it:
> dim.list = function(x) c(length(x[[1]]), length(x))
> dim(list(1))
NULL
> dim.list(list(1))
[1] 1 1
What is the correct way of registering dim.list with .Primitive("dim")?
Thanks,
Vadim
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2004 Sep 27
2
passing formula arg to mgcv::gam
Hi,
I have a function, callGam, that fits a gam model to a subset of a dataframe. The argument to callGam is a formula, the subset is determined inside the function itself. My na??ve approach generates and error, see below. I guess this is because 'idx' is loocked up in the environment of 'formula', but I am too ignorant about environments to be able to tell for sure. Could
2004 May 01
5
skip lines on a connection
Hi,
I am looking for an efficient way of skipping big chunks of lines on a
connection (not necessarily at the beginning of the file). One way is to
use read lines, e.g. readLines(1e6), but a) this incurs the overhead of
construction of the return char vector and b) has a (fairly remote)
potential to blow up the memory.
Another way would be to use scan(), e.g.
scan(con, skip=1e6, nmax=0)
2003 Sep 03
3
read.table: check.names arg - feature request
Hi,
I thought it would be convenient if the check.names argument to read.table, which currently can only be TRUE/FALSE, could take a function value as well. If the function is supplied it should be used instead of the default make.names.
Here is an example where it can come in handy. I tend to keep my data in coma-separated files with a header line. The header line is prefixed with a comment
2005 Mar 08
4
how modify object in parent.env
Hi,
Is it possible to modify an object in the parent.env (as opposed to
re-bind)? Here is what I tried:
> x = 1:3
# try to modify the first element of x from within a new environment
> local(get("x", parent.env(environment()))[1] <- NA)
Error in eval(expr, envir, enclos) : Target of assignment expands to
non-language object
# On the other hand retrieval works just fine
>
2001 Sep 17
3
computational capacity of Linux network
Hi, This is not an R question per ce, but I feel like this is a right
community to ask it.
As a part of our work we run a lot of non-interactive computational jobs. To
increase the throughput we would like to distribute the load over the entire
network and we are looking at Linux network as a platform. Ideally we would
like to be able to submit a job to the network, rather than to a computer,
and
2004 Jun 14
5
mkChar can be interrupted
Hi,
As was discussed earlier in another thread and as documented in R-exts
.Call() should not be interruptible by Ctrl-C. However the following
code, which spends most of its time inside mkChar, turned out to be
interruptible on RH-7.3 R-1.8.1 gcc-2.96:
#include <Rinternals.h>
#include <R.h>
SEXP foo0(const SEXP nSexp) {
int i, n;
SEXP resSexp;
if (!isInteger(nSexp))
2004 Jun 30
2
Slow IO: was [R] naive question
I believe IO in R is slow because of the way it is implemented, not
because it has to do some extra work for the user.
I compared scan() with 'what' argument set (which is, AFAIK, is the
fastest way to read a CSV file) to an equivalent C code. It turned out
to be 20 - 50 times slower.
I can see at least two main reasons why R's IO is so slow (I didn't
profile this though):
A) it
2005 Apr 12
5
How allocate STRSXP outside of gc
Hi,
I am trying to figure a way to allocate a string SEXP so that gc() won't
ever collect it.
Here is a little bit of a background. Suppose I want to write a
.Call-callable function that upon each call returns the same value, say
mkChar("foo"):
SEXP getFoo() {
return mkChar("foo");
}
The above implementation doesn't take advantage of the fact that
2004 Mar 17
4
why-s of method dispatching
Hi,
I am having a problem to understand why as.data.frame method doesn't
dispatch properly on my class:
> setClass("Foo", "character")
[1] "Foo"
> as.data.frame(list(foo=new("Foo", .Data="a")))
Error in as.data.frame.default(x[[i]], optional = TRUE) :
can't coerce Foo into a data.frame
I was expecting that this would call
2004 Nov 26
2
Lightweight data frame class
Hi,
As far as I can tell data.frame class adds two features to those of
lists:
* matrix structure via [,] and [,]<- operators (well, I know these are
actually "["(i, j, ...), not "[,]").
* row names attribute.
It seems that the overhead of the support for the row names, both
computational and RAM-wise, is rather non-trivial. I frequently
subscript from a data.frame,
2005 Dec 09
3
[R] data.frame() size
Hi,
Please see below for post on r-help regarding data.frame() and the
possibility of dropping rownames, for space and time reasons.
I've made some changes, attached, and it seems to be working well. I see the
expected space (90% saved) and time (10 times faster) savings. There are no
doubt some bugs, and needs more work and testing, but I thought I would post
first at this stage.
Could some
2004 Dec 03
4
seq.Date requires by
Hi,
What is the reason for seq.Date to require the 'by' argument and not to
default it to 1 in the example below?
> seq(from=as.Date("1996-01-01"), to=as.Date("1996-12-01"))
Error in seq.Date(from = as.Date("1996-01-01"), to =
as.Date("1996-12-01")) :
exactly two of `to', `by' and `length.out' / `along.with' must be
specified
2003 Feb 19
4
fitting a curve according to a custom loss function
Dear R-Users,
I need to find a smooth function f() and coefficients a_i that give the best
fit to
y ~ a_0 + a_1*f(x_1) + a_2*f(x_2)
Note that it is the same non-linear transformation f() that is applied to
both x_1 and x_2.
So my first question is how can I do it in R?
A more general question is this: suppose I have a utility function U(a_i,
f()), where f() is say a spline. Is there a general
2005 Mar 22
1
documentation on seek *does not* need update
Well, "integer" is also a storage.mode in R. It is not immediately clear
which meaning the help page uses. I guess some extra elaboration would
be helpful.
Anyway, thank you for the clarification,
Vadim
> -----Original Message-----
> From: Prof Brian Ripley [mailto:ripley@stats.ox.ac.uk]
> Sent: Tuesday, March 22, 2005 9:54 AM
> To: Vadim Ogranovich
> Cc:
2004 Apr 23
3
time zones in POSIXt
Hi,
I have two data sources. One records time in PST time zone, the other in
GMT. I want to compute the difference between the two, but don't see
how. Here is an example where I compute time difference between
identical times each (meant to be) relative to its time zone.
> as.POSIXlt("2000-05-10 10:15:00", "PST") - as.POSIXlt("2000-05-10
10:15:00",
2004 Jun 08
5
fast mkChar
Hi,
To speed up reading of large (few million lines) CSV files I am writing
custom read functions (in C). By timing various approaches I figured out
that one of the bottlenecks in reading character fields is the mkChar()
function which on each call incurs a lot of garbage-collection-related
overhead.
I wonder if there is a "vectorized" version of mkChar, say mkChar2(char
**, int
2004 Nov 10
3
recursive default argument reference
Hi,
It seems that a formal function argument can not default to an "outer"
variable of the same name:
> x <- "foo"
> ff <- function(x=x) x
> ff()
Error in ff() : recursive default argument reference
>
Is this intentional? Why?
I use R-1.9.1.
Thanks,
Vadim