Displaying 20 results from an estimated 4000 matches similar to: "optim or nlm with matrices"
2002 Nov 09
2
importing data from Excel using RODBC
Hi,
I used RODBC to import data from an Excel spreadsheet "*.xls", but some
columns were returned as zeros. When I looked at these columns in Excel, I
found that thery are results of formula calculations and not entry. My
question is: Is there any parameter or command I need to use in order to
overcome this problem?
Thank you
Ahmad Abu Hammour
2002 Apr 19
4
Durbin-Watson test in packages "car" and "lmtest"
Hi,
P-values in Durbin-Watson test obtained through the use of functions available in packages "lmtest" and "car" are different. The difference is quite significant. function "dwtest" in "lmtest" is much faster than "burbinwatson" in "car". Actually, you can take a nap while the latter trying to calculated Durbin-Watson test. My question
1999 Nov 07
2
arima0() (PR#314)
Full_Name: Ahmad Abu Hammour
Version: rw0651
OS: windows 95
Submission from: (NULL) (63.23.128.44)
Although I know that "ts package" is preliminary, I wanted to compare the
results from R and SPSS. I ran ARIMA(2,1,2) in both softwares. I got NaN in
standard errors of coefficients from R and real figures from SPSS. I changed
"delta" in R to match that used by SPSS, I received
2002 Sep 09
1
impulse response function
Hi,
Is there a function in any of R-packages that can produce and plot the
impulse response function for any model..
Thank you
Ahmad Abu Hammour
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2002 Nov 16
1
using the function "expression" with "paste" in a plot
Hi,
I noticed that paste and expression in the following manner does not produce
the desired result.
vnames=c("pi","y","delta")
vx=vn=3
m=16
# mydata any matrix that takes for the following form
mydata=array(somedata,c(m,vn,vx))
# producing plots
for (j in 1:vx){
for (i in 1:vn)
{
plot(mydata, type="l", main=expression(paste("Effect of",
2015 Feb 23
5
iterated lapply
Hi everybody,
with the following code I generate a list of functions. Each function
reflects a "condition". When I evaluate this list of functions by
another lapply/sapply, I get an unexpected result: all values coincide.
However, when I uncomment the print(), it works as expected. Is this a
bug or a feature?
conditions <- 1:4
test <- lapply(conditions, function(mycondition){
2008 Jul 17
2
nested calls, variable scope
Below is an example of a problem I encounter repeatedly when I write functions. A call works at the command line, but it does not work inside a function, even when I have made sure that all required variables are available within the function. The only way I know to solve it is to make the required variable global, which of course is dangerous. What is the elegant or appropriate way to solve
2015 Feb 24
3
iterated lapply
From: Daniel Kaschek <daniel.kaschek at physik.uni-freiburg.de>
> ... When I evaluate this list of functions by
> another lapply/sapply, I get an unexpected result: all values coincide.
> However, when I uncomment the print(), it works as expected. Is this a
> bug or a feature?
>
> conditions <- 1:4
> test <- lapply(conditions, function(mycondition){
>
2000 Sep 20
1
lag() and lm()
Hi,
I am using R interactively for estimation and even data manipulation. I want
to use lag() function within lm() function in a way looks like:
mymodel<- lm(y~x+I(lag(y,-1)-1, data=anydata)
What I get is always perfect fit; (that is, coefficient=1) which is not
true.
If the model looks like
mymodel<- lm(y~z+x+I(lag(x,-1)-1, data=anydata)
summary returns only one coefficient for x and
2007 Jun 15
0
Question with nlm
Hi,
I would really appreciate if I could get some help here. I'm using nlm to minimize my negative log likelihood function. What I did is as follows:
My log likelihood function (it returns negative log likelihood) with 'gradient' attribute defined inside as follows:
# ==========Method definition======================
logLikFunc3 <- function(sigma, object, totalTime) {
y <-
2010 Aug 25
3
What does this warning message (from optim function) mean?
Hi R users,
I am trying to use the optim function to maximize a likelihood funciton, and
I got the following warning messages.
Could anyone explain to me what messege 31 means exactly? Is it a cause for
concern?
Since the value of convergence turns out to be zero, it means that the
converging is successful, right?
So can I assume that the parameter estimates generated thereafter are
reliable MLE
2002 Sep 03
1
t(xmat)
Hi,
I have a matrix and time series "xmat". I have no problem executing any matrix functions except t(xmat) which gives the following error message. My question if "xmat" is a matrix why I can not execute this matrix function?? converting the time series and matrix into a data frame solves the problem
>dim(xmat)
[1] 98 7
> t(xmat)
Error in "tsp<-"(*tmp*,
2002 Apr 09
2
Restricted Least Squares
Hi,
I need help regarding estimating a linear model where restrictions are imposed on the coefficients. An example is as follows:
Y_{t+2}=a1Y_{t+1} + a2 Y_t + b x_t + e_t
restriction
a1+ a2 =1
Is there a function or a package that can estimate the coefficient of a model like this? I want to estimate the coefficients rather than test them.
Thank you for your help
Ahmad Abu Hammour
--------------
2015 Feb 26
3
iterated lapply
Would introducing the new frame, with the call to local(), cause problems
when you use frame counting instead of <<- to modify variables outside the
scope of lapply's FUN, I think the frame counts may have to change. E.g.,
here is code from actuar::simul() that might be affected:
x <- unlist(lapply(nodes[[i]], seq))
lapply(nodes[(i + 1):(nlevels - 1)],
2012 Sep 19
0
[LLVMdev] newbie question on getelementptr
Hi Óscar,
Thank you for your prompt reply. Unfortunately, I still need more guidance
as using the Demo page to generate C++ code didn't result in a global
variable being used.
Basically, I'm following your advice to use a LoadInst:
Value *v = new LoadInst(result, "", theBasicBlock);
Function *myfn = cast<Function>(v);
I was not sure how I could get a BasicBlock for the
2015 Feb 24
2
iterated lapply
> On Feb 24, 2015, at 10:50 AM, <luke-tierney at uiowa.edu> wrote:
>
> The documentation is not specific enough on the indented semantics in
> this situation to consider this a bug. The original R-level
> implementation of lapply was
>
> lapply <- function(X, FUN, ...) {
> FUN <- match.fun(FUN)
> if (!is.list(X))
> X <-
2011 Dec 12
2
Problems in building a DLL in 64-bit Windows
I am trying to build a C language DLL and it works well with i386 but when I compile with it substituted
by x64, like the FAQ page says, the result is an error message:
C:/PROGRA~1/R/R-214~1.0/bin/x64/R.ddl: file not recognized : File format not recognized
collect2: ld returned 1 exit status
How can I solve this? The problem is with R 2-14.0 and 2-13.0
The complete source code is
/*
* myfun.c
2010 Mar 05
1
How to parse the arguments from a function call and evaluate them in a dataframe?
Hi,
I would like to write a function which has the following syntax:
myfn <- function(formula, ftime, fstatus, data) {
# step 1: obtain terms in `formula' from dataframe `data'
# step 2: obtain ftime from `data'
# step 3: obtain fstatus from `data'
# step 4: do model estimation
# step 5: return results
}
The user would call this function as:
myfn(formula=myform,
2000 Oct 06
1
Formulae with factors that have missing values
Hi All,
I have a formula which has a factor with NAs in it. I wish to keep
these in the model matrix, but the NA information is currently lost (the
rows are kept but the NA gets converted to 0). Any ideas as to how
I can keep NAs in?
e.g.
junk <-
2018 May 05
1
adding overall constraint in optim()
Hi,
You can use the projectLinear argument in BB::spg to optimize with linear equality/inequality constraints.
Here is how you implement the constraint that all parameters sum to 1.
require(BB)
spg(par=p0, fn=myFn, project="projectLinear", projectArgs=list(A=matrix(1, 1, length(p0)), b=1, meq=1))
Hope this is helpful,
Ravi
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