Displaying 20 results from an estimated 2000 matches similar to: "Puzzled at a trivial function using Hmisc::setps"
2008 Mar 18
3
Puzzled at generating combinations
I have two data frames. Suppose the first has rows
r1
r2
r3
and the second has rows
R1
R2
R3
I'd like to generate the data frame:
r1 R1
r1 R2
r1 R3
r2 R1
r2 R2
r2 R3
r3 R1
r3 R2
r3 R3
How would I go about doing this? I'm sure there's a clean way to do it
but I find myself thinking in loops.
--
Ajay Shah
2005 Jun 14
1
Puzzled in utilising summary.lm() to obtain Var(x)
I have a program which is doing a few thousand runs of lm(). Suppose
it is a simple model
y = a + bx1 + cx2 + e
I have the R object "d" where
d <- summary(lm(y ~ x1 + x2))
I would like to obtain Var(x2) out of "d". How might I do it?
I can, of course, always do sd(x2). But it would be much more
convenient if I could snoop around the contents of summary.lm and
2007 Sep 28
6
Graphics and LaTeX documents with the same font
Dear All,
I know how to export graphics as pdf files and then how to include
them in LaTeX documents. However, I do not know how to do in order to
have the text of the graphics written with the font selected for the
LaTeX document. Is that possible?
Thanks in advance,
Paul
2005 Aug 04
1
Puzzled at rpart prediction
I'm in a situation where I say:
> predict(m.rpart, newdata=D[N1+t,])
0 1
173 0.8 0.2
which I interpret as meaning: an 80% chance of "0" and a 20% chance of
"1". Okay. This is consistent with:
> predict(m.rpart, newdata=D[N1+t,], type="class")
[1] 0
Levels: 0 1
But I'm puzzled at the following. If I say:
> predict(m.rpart,
2005 Jul 12
2
Puzzled at ifelse()
I have a situation where this is fine:
> if (length(x)>15) {
clever <- rr.ATM(x, maxtrim=7)
} else {
clever <- rr.ATM(x)
}
> clever
$ATM
[1] 1848.929
$sigma
[1] 1.613415
$trim
[1] 0
$lo
[1] 1845.714
$hi
[1] 1852.143
But this variant, using ifelse(), breaks:
> clever <- ifelse(length(x)>15, rr.ATM(x, maxtrim=7), rr.ATM(x))
2007 Oct 01
1
Graphics and LaTeX documents with the same font - multiple y-axes
Well,
I agree that plots with multiple y-axes can be very confusing but .... i am not sure that always they are also misleading .... One time i was asked to make a 2 y-axes plot, one y axes was for elevation (heights in meters) and one for rugosity (values between 1 and 2 - unitless). The idea was to visualize that for a more complex profile the rugosity is higher than for a flatter terrain. A
2004 Aug 21
3
Puzzled at lm() and time-series
I tried toy problems and there doesn't seem to be a basic problem
between lm() and ts objects:
X = data.frame(x=c(1,2,7,9), y=c(7,2,3,1))
lm(y ~ x, X)
X <- lapply(X, function(x) ts(x, frequency=12, start=c(1994,7)))
lm(y ~ x, X)
and this works fine - whether you do an lm() before or after making ts
objects, it's okay.
But I have a situation where things aren't okay.
2007 Aug 31
2
Bugreport on integration of Sweave and latex beamer
I think I have isolated a problem with integration between Sweave and beamer.
Could you please see the file:
http://www.mayin.org/ajayshah/tmp/bugdemo.Rnw
Unfortunately, it uses some of my internal libraries, so you can't run
it. When I put it through Sweave, I get:
http://www.mayin.org/ajayshah/tmp/bugdemo.tex
which is, of course, a generic latex file which you can read and
2006 Jun 25
1
Puzzled with contour()
Folks,
The contour() function wants x and y to be in increasing order. I have
a situation where I have a grid in x and y, and associated z values,
which looks like this:
x y z
[1,] 0.00 20 1.000
[2,] 0.00 30 1.000
[3,] 0.00 40 1.000
[4,] 0.00 50 1.000
[5,] 0.00 60 1.000
[6,] 0.00 70 1.000
[7,] 0.00 80 0.000
[8,] 0.00 90
2005 Jun 07
1
R and MLE
I learned R & MLE in the last few days. It is great! I wrote up my
explorations as
http://www.mayin.org/ajayshah/KB/R/mle/mle.html
I will be most happy if R gurus will look at this and comment on how
it can be improved.
I have a few specific questions:
* Should one use optim() or should one use stats4::mle()?
I felt that mle() wasn't adding much value compared with optim, and
2004 May 27
3
Date parsing question
How do I parse a date "yyyymmdd"? I tried asking chron(s, "ymd") but
that didn't work. Would the date parsing routines of the Date class of
1.9 grok this?
--
Ajay Shah Consultant
ajayshah at mayin.org Department of Economic Affairs
http://www.mayin.org/ajayshah Ministry of Finance, New Delhi
2008 Oct 15
2
"Heuristic optimisation"?
I wondered was people on this list felt about this article:
http://www.voxeu.org/index.php?q=node/2363
which talks about the problems of obtaining sound answers in numerical
optimisation in settings such as MLE or NLS.
--
Ajay Shah http://www.mayin.org/ajayshah
ajayshah at mayin.org http://ajayshahblog.blogspot.com
<*(:-? -
2004 Aug 17
1
An entire data frame which is a time-series?
I have :
raw <- read.table("monthly.text", skip=3, sep="|",
col.names=c("junk", "junk2",
"wpi", "g.wpi", "wpi.primary", "g.wpi.primary",
"wpi.fuel", "g.wpi.fuel", "wpi.manuf", "g.wpi.manuf",
2008 Mar 17
4
How does one do simple string concatenation?
How does one convert objects c("a","b","c") and "d" into "abcd"?
> paste(c("a","b","c"), "d")
of course yields
[1] "a d" "b d" "c d"
--
Ajay Shah http://www.mayin.org/ajayshah
ajayshah at mayin.org
2009 Mar 15
1
Stuck on building a package
Folks,
I have a personal package which used to build fine. Today when I tried
to build the package again, some errors popped up. Could you please
help? When I paste the offending function into an R it works
correctly. But the package build breaks.
$ R CMD check ansecon
* checking for working pdflatex ... OK
* using log directory '/Users/ajayshah/L/R/packages/ansecon.Rcheck'
* using R
2007 May 27
0
Not able to understand the behaviour of boot
Folks,
I have a time-series of 875 readings of the weekly returns of a stock
market index (India's Nifty). I am interested in the AR(1)
coefficient. When I do arima(r, order=c(1,0,0)) I get a statistically
significant AR1 coefficient.
If we apply the ordinary bootstrap to this problem, this involves
sampling with replacement, which destroys the time-series
structure. Hence, if we do
2004 Jun 13
0
MCMC tutorials
Hi Ajay:
A casual search of google using terms like "MCMC", "Markov Chains", "Monte
Carlo", and "tutorial" pulled up over 4000 hits. A few links that may
interest you, I thought, like:
http://csep1.phy.ornl.gov/CSEP/MC/MC.html
http://www.stat.fi/isi99/proceedings/arkisto/varasto/gree0167.pdf
http://www.maths.soton.ac.uk/staff/Sahu/utrecht/
...
and so
2007 Oct 28
1
maximizing a function
See
http://mayin.nfshost.com/ajayshah/KB/R/documents/mle/mle.html
--
Ajay Shah http://www.mayin.org/ajayshah
ajayshah at mayin.org http://ajayshahblog.blogspot.com
<*(:-? - wizard who doesn't know the answer.
2004 Feb 09
1
Subset function of lm(); "rolling regressions"
Folks,
I asked a question on this mailing list about the subset support of
lm(). In a flash, I got three helpful responses from
Rajarshi Guha <rxg218 at psu.edu> <http://jijo.cjb.net>
Erin Hodgess <hodgess at gator.uhd.edu>
and
Peter Dalgaard <p.dalgaard at biostat.ku.dk>
:-) and it was just great.
The mistake I was making was in not understanding the notion of a
2008 Mar 05
1
New data source - now how do we build an R interface?
Folks,
A nice new data resource has come up -- http://data.un.org/
I thought it would be wonderful to setup an R function like
tseries::get.hist.quote() which would be able to pull in some or all
of this data.
I walked around a bit of it and I'm not able to map the resources to
predictable URLs which can then be wget. There's some javascript going
on that I'm not understanding.