Displaying 20 results from an estimated 600 matches similar to: "nls() fit to a lorentzian - can I specify partials?"
2023 Jan 11
1
return value of {....}
I am more than a little puzzled by your question.
In the construct {expr1; expr2; expr3} all of the
expressions expr1, expr2, and expr3 are evaluated,
in that order. That's what curly braces are FOR.
When you want some expressions evaluated in a
specific order, that's why and when you use curly
braces. If that's not what you want, don't use them.
Complaining about it is like
2023 Jan 13
1
return value of {....}
R's
{ expr1; expr2; expr3}
acts much like C's
( expr1, expr2, expr3)
E.g.,
$ cat a.c
#include <stdio.h>
int main(int argc, char* argv[])
{
double y = 10 ;
double x = (printf("Starting... "), y = y + 100, y * 20);
printf("Done: x=%g, y=%g\n", x, y);
return 0;
}
$ gcc -Wall a.c
$ ./a.out
Starting... Done: x=2200, y=110
I don't like that
2023 Jan 09
5
return value of {....}
Dear members,
I have the following code:
> TB <- {x <- 3;y <- 5}
> TB
[1] 5
It is consistent with the documentation: For {, the result of the last expression evaluated. This has the visibility of the last evaluation.
But both x AND y are created, but the "return value" is y. How can this be advantageous for solving practical problems?
2001 May 30
2
environments
I would like to be able, inside a function, to create a new function, and
use it as part of a formula as an argument to, say, gnls or nlme. for
example:
MyTop <- function(data=dta) {
Cexp <- function(dose,A,B,m){...}
Model <- as.formula(paste("y","~ Cexp(",paste(formals(Cexp),collapse
=", "),")"))
MyCall <-
2023 Jan 12
4
return value of {....}
Hello Akshay,
R is quite inspired by LISP, where this is a common thing. It is not in fact that {...} returned something, rather any expression evalulates to some value, and for a compound statement that is the last evaluated expression.
{...} might be seen as similar to LISPs (begin ...).
Now this is a very different thing compared to {...} in something like C, even if it looks or behaves
2005 Mar 29
2
strange error with rw2010dev
With rw2010dev I get a strange protect(): protection stack overflow
error with a small data frame which otherwise is usable:
If anybody wants to have a look I can provide an RData file
with the problematic data frame.
Doesn't seem to be necessary, the following simulated example
generates the error:
> testmat <- matrix(1:80, 20,4)
> dim(testmat)
[1] 20 4
> str(testmat)
int
2011 May 23
1
Applying boxplot.stats to multiple value lists
Hello all R gurus,
I have a following problem which I hope someone will help me to solve.
I have a data.frame in form similar to below. > testframe<-data.frame("Name"=c("aa","aa","aa","aa","aa","bb","bb","bb","bb","bb"),"Value"=c(1,100,1,1,1,100,100,100,100,1))
2003 May 09
2
Data-mining using R
Is it possible to use R as a data-mining tool? Here's the problem I've
got. I have a couple of data sets consisting of results from a cDNA
microarray experiment - the details about the biology don't really matter here, the
same theory applies for any other data-mining task (that's why I thought it'd
be more appropriate to post this on r-user). Each of these datasets consists
2012 Jun 09
1
Applying a function to a column of a data frame
Apologees the novice question. Currently climbing up the learning curve of R.
Suppose I have the following function and the data.frame:
testfun<-function(x=1,y=2) x+y
testframe=data.frame(col1=c(1,2),col2=c(3,4))
When evaluating testfun, I want to use the default value for y (which
is 2) and for x, I want to feed (one by one) the values in col2 of
testframe. How can I achieve this please?
2012 Jun 10
3
Data.frames can not hold objects...What can be done in the following scenario?
R-Help community,
I understand that data.frames can hold elements of type double, string
etc but NOT objects (such as a matrix etc). This is not convenient for
me in the following situation. I have a function that takes 2 inputs
and returns a vector:
testfun <- function (x,y) seq(x,y,1)
I have a data.frame defined as follows:
testframe<-data.frame(xvalues=c(2,3),yvalues=c(4,5))
I would
2004 May 14
1
covariates in lm
Dear R list,
I have been trying to do a linear model, extracting the effect of a
covariate.... and the results do not match, when I do it with other programs
(e.g. minitab).... so it is obvious that I was doing something wrong.
Whan I do it with minitab, I have this results: (sector is a factor and depth
is the covariate):
Source DF Seq SS Adj SS Adj MS F P
2018 Jan 04
3
silent recycling in logical indexing
Hmm.
Chuck: I don't see how this example represents
incomplete/incommensurate recycling. Doesn't TRUE replicate from
length-1 to length-3 in this case (mat[c(TRUE,FALSE),2] would be an
example of incomplete recycling)?
William: clever, but maybe too clever unless you really need the
speed? (The clever way is 8 times faster in the following case ...)
x <- rep(1,1e6)
2012 Oct 18
3
Upper limit in nlsLM not working as expected
Dear all,
I am using the nlsLM function to fit a Lorentzian function to my experimental data.
The LM algorithm should allow to specify limits, but the upper limit appears not to work as expected in my code.
The parameter 'w', which is peak width at half maximuim always hits the upper limit if the limit is specified. I would expect the value to be in-between the upper and lower limit with
2007 Jul 30
2
deriv, loop
Hi, 2 questions:
Question 1: example of what I currently do:
for(i in 1:6){sink("temp.txt",append=TRUE)
dput(i+0)
sink()}
x=scan(file="temp.txt")
print(prod(x))
file.remove("C:/R-2.5.0/temp.txt")
But how to convert the output of the loop to a vector that I can manipulate
(by prod or sum etc), without having to write and append to a file?
Question 2:
>
2006 Nov 18
1
deriv when one term is indexed
Hi,
I'm fitting a standard nonlinear model to the luminances measured
from the red, green and blue guns of a TV display, using nls.
The call is:
dd.nls <- nls(Lum ~ Blev + beta[Gun] * GL^gamm,
data = dd, start = st)
where st was initally estimated using optim()
st
$Blev
[1] -0.06551802
$beta
[1] 1.509686e-05 4.555250e-05 7.322720e-06
$gamm
[1] 2.511870
This works fine but I
2006 Oct 27
2
all.names() and all.vars(): sorting order of functions' return vector
Dear list-subscriber,
in the process of writing a general code snippet to extract coefficients
in an expression (in the example below: 0.5 and -0.7), I stumbled over
the following peculiar (at least peculiar to me:-) ) sorting behaviour
of the function all.names():
> expr1 <- expression(x3 = 0.5 * x1 - 0.7 * x2)
> all.names(expr1)
[1] "-" "*" "x1"
2006 Jul 18
2
I think this is a bug
Hello!
I work with:
R : Copyright 2006, The R Foundation for
Statistical Computing
Version 2.3.1 (2006-06-01)
On Windows XP Professional (Version 2002) SP2
I think there is a bug in the conditional
execution if (expr1) {expr2} else {expr3}
If I try:
"if (expr1) expr2 else expr3"
it works well but when I put the expression expr2
and expr3 between {} I receive an error message
2023 Jan 09
2
return value of {....}
Unless you do something special within a function, only the value(s)
returned are available to the caller. That is the essence of
functional-type programming languages.
You need to read up on (function) environments in R . You can search on
this. ?function and its links also contain useful information, but it may
too terse to be explicable to you. There are of course many available
references on
2014 May 01
3
How to test if an object/argument is "parse tree" - without evaluating it?
This may have been asked before, but is there an elegant way to check
whether an variable/argument passed to a function is a "parse tree"
for an (unevaluated) expression or not, *without* evaluating it if
not?
Currently, I do various rather ad hoc eval()+substitute() tricks for
this that most likely only work under certain circumstances. Ideally,
I'm looking for a isParseTree()
2023 Jan 09
1
return value of {....}
?s 14:47 de 09/01/2023, akshay kulkarni escreveu:
> Dear members,
> I have the following code:
>
>> TB <- {x <- 3;y <- 5}
>> TB
> [1] 5
>
> It is consistent with the documentation: For {, the result of the last expression evaluated. This has the visibility of the last evaluation.
>
> But both x AND y are created, but the