Displaying 20 results from an estimated 30000 matches similar to: "model.matrix(.) and all that"
2008 Apr 05
2
Adding a Matrix Exponentiation Operator
Hi all
I recently started to write a matrix exponentiation operator for R (by
adding a new operator definition to names.c, and adding the following code
to arrays.c). It is not finished yet, but I would like to solicit some
comments, as there are a few areas of R's internals that I am still feeling
my way around.
Firstly:
1) Would there be interest in adding a new operator %^% that performs
1997 Dec 08
3
R-alpha: Bug in tapply in the Windows version of September
The function tapply is not working in the Windows version of R=20
(Version 0.50 Beta (Sept 29, 1997))
In
tapply <- function (x, INDEX, FUN=3DNULL, simplify=3DTRUE, ...)=20
...
The part:
if (simplify && all(unlist(lapply(ans, length)) =3D=3D 1)) {
ans <- unlist(ans, recursive =3D FALSE)
names(ans)<-namelist[[1]]
return(ans)
}
should be replaced by
if (simplify
2017 Jan 26
3
RFC: tapply(*, ..., init.value = NA)
Last week, we've talked here about "xtabs(), factors and NAs",
-> https://stat.ethz.ch/pipermail/r-devel/2017-January/073621.html
In the mean time, I've spent several hours on the issue
and also committed changes to R-devel "in two iterations".
In the case there is a *Left* hand side part to xtabs() formula,
see the help page example using 'esoph',
it
2008 Dec 16
2
Problem assigning "NA" as a level name in a list
I want to generate a list (called "dataList" below) where each of its
levels is named. These names are assigned to nameList, which contains
all possible permutations of size two taking letters from a larger
alphabet, e.g., "aa",...,"Fd",..,"Z1",... One of these permutations is
the character string "NA". It seems that when I try to name one
2005 Apr 16
2
String in data frame
hello,
how can take the string in the data frame.
right now i have a table that create as a data frame and stored in the file called "data.xls" and now i want to read data frame as a table in my another r program, i used the following command:
the first column of the data frame is just one number called "num", but the second one a list of string, called "name".
d
2017 Jan 26
2
RFC: tapply(*, ..., init.value = NA)
On a related note, the storage mode should try to match ans[[1]] (or
unlist:ed and) when allocating 'ansmat' to avoid coercion and hence a full
copy.
Henrik
On Jan 26, 2017 07:50, "William Dunlap via R-devel" <r-devel at r-project.org>
wrote:
It would be cool if the default for tapply's init.value could be
FUN(X[0]), so it would be 0 for FUN=sum or FUN=length, TRUE
2000 Apr 04
0
stochastic process transition probabilities estimation
Hi all,
I'm new with R (and S), and relatively new to statistics (I'm a
computer scientist), so I ask sorry in advance if my question is silly.
My problem is this: I have a (sample of a) discrete time stochastic
process {X_t} and I want to estimate
Pr{ X_t | X_{t-l_1}, X_{t-l_2}, ..., X_{t-l_k} }
where l_1, l_2, ..., l_k are some fixed time lags. It will be enough for
me to compute
1998 Nov 08
1
Strange behaviour of lm
R-0.62.4 running under linux
-------------------------------------------------------------------------------
> x <- rnorm(10)
> lm(x~x)
Error: length of namelist must equal dims
> x <- c(1,2,3)
> lm(x~x)
Call:
lm(formula = x ~ x)
Coefficients:
(Intercept)
2
> y <- x
> lm(y~x)
Call:
lm(formula = y ~ x)
Coefficients:
(Intercept) x
2011 Apr 21
1
problem subsetting of a reference class
I am trying to define subset operator for a reference class and hitting some
problem i am unable to diagnose.To give an example, here is a toy class
generator that is a wrapper around a list
tmpGEN<-setRefClass("TMP", fields=list(
namelist="list"
))
tmpGEN$methods('add'=function(obj, name){
namelist[[name]]<<-obj
})
2015 Feb 03
2
Seed in 'parallel' vignette
Hi,
This is most likely only a minor technicality, but I saw the
following: On page 6 of the 'parallel' vignette
(http://stat.ethz.ch/R-manual/R-devel/library/parallel/doc/parallel.pdf),
the random-number generator "L'Ecuyer-CMRG" is said to have seed
"(x_n, x_{n-1}, x_{n-2}, y_n, y_{n-1}, y_{n-2})". However, in L'Ecuyer
et al. (2002), the seed is given with
2002 Sep 04
3
strange things with eval and parent frames
Dear mailing list,
I have found some strange behaviour which I think relates to parent frames
and eval. Can anyone explain what's going on here?
First example:
> test.parent.funcs_ function() {
outer.var_ 5
subfunc1_ function() substitute( outer.var, envir=parent.frame())
print( subfunc1())
subfunc2b_ function() eval( quote( outer.var), envir=parent.frame())
print(
2007 Jul 31
1
[Bridge] brctl uses incorrect sysfs path
Hi,
I noticed that brctl (or more accurately, libbridge) is using the wrong path
when doing various lookups in sysfs: e.g. /sys/class/net/brXXX/stp_state
when it should use /sys/class/net/brXXX/bridge/stp_state. This doesn't
cause any problems on most systems as it falls back to the ioctl when the
sysfs attempt fails; however the ioctl method is apparently deprecated. I
believe the
2001 Feb 08
2
dnbinom(,size<1,)=0 (PR#842)
This came up on r-help but indicates a bug.
dnbinom(x,n,p) calls dbinom_raw(n-1,...)
which returns 0 for n<1.
-thomas
---------- Forwarded message ----------
Date: Thu, 08 Feb 2001 17:10:23 +0000
From: Yudi Pawitan <yudi@stat.ucc.ie>
To: Mark Myatt <mark@myatt.demon.co.uk>
Cc: R-Help <r-help@stat.math.ethz.ch>
Subject: Re: [R] Goodness of fit to Poisson / NegBinomial
2006 Sep 14
1
Rv generation
Hi,
Can Someone inform me how to generate RV's using the below CDF, by inverse
technique.
Thanks for your help and time.
My CDF is as follows
\[
F(x)=0 \ \text{if} \ x < 0\]\[
F(x)=\{\frac{x-x_i}{x_{i+1}-x_{i}}*(p_{i+1}-p_{i})\}+p_{i}\
\forall \ x_{i}\leq x < x_{i+1} \]
\[ F(x)=1 \ \text{if} \ x > x_{i+1}
\]
Regards
Murthy
2009 Oct 11
2
Why H1=1? (H's the hat matrix)
Suppose I have the following hat matrix:
H=X(X'X)^{-1}X'
X is a n by p matrix, where n >= p and X_{i,1} = 1
I'm wondering why H1 = 1. (Here, 1 is column vector, whose each
element is the number 1)
Thank you!
2008 Apr 15
1
by inconsistently strips class - with fix
summary:
The function 'by' inconsistently strips class from the data to which
it is applied.
quick reason:
tapply strips class when simplify is set to TRUE (the default) due to
the class stripping behaviour of unlist.
quick answer:
This can be fixed by invoking tapply with simplify=FALSE, or changing
tapply to use do.call(c instead of unlist
executable example:
2013 Mar 11
3
How to obtain the original indices of elements after sorting
Dear All,
Suppose I have a vector X = (x_1, x_2, ...., x_n), X_sort = sort(X)
= (x_(1), x_(2), ... , x(n) ),
and I would like to know the original position of these ordered x_(i)
in X, how can I do it?
case 1: all values are unique
x <- c( 3, 5, 4, 6)
x.sort <- sort(x) #
# I would like to obtain a vector (1, 3, 2, 4) which indicates that 3
in x is still the 1st element in x.sort, 5 is at
2012 Jun 25
4
do.call or something instead of for
Dear R users,
I'd like to compute X like below.
X_{i,t} = 0.1*t + 2*X_{i,t-1} + W_{i,t}
where W_{i,t} are from Uniform(0,2) and X_{i,0} = 1+5*W_{i,0}
Of course, I can do this with "for" statement, but I don't think it's good
idea because "i" and "t" are too big.
So, my question is that
Is there any better idea to avoid "for" statement
2004 Apr 08
1
Why are Split and Tapply so slow with named vectors, why is a for loop faster than mapply
First, here's the problem I'm working on so you understand the context. I
have a data frame of travel activity characteristics with 70,000+ records.
These activities are identified by unique chain numbers. (Activities are
part of trip chains.) There are 17,500 chains.
I use the chain numbers as factors to split various data fields into lists
of chain characteristics with each element of
2017 Jan 27
1
RFC: tapply(*, ..., init.value = NA)
On Fri, Jan 27, 2017 at 12:34 AM, Martin Maechler
<maechler at stat.math.ethz.ch> wrote:
>
> > On Jan 26, 2017 07:50, "William Dunlap via R-devel" <r-devel at r-project.org>
> > wrote:
>
> > It would be cool if the default for tapply's init.value could be
> > FUN(X[0]), so it would be 0 for FUN=sum or FUN=length, TRUE for
>