Displaying 16 results from an estimated 16 matches for "puromycin".
2006 Nov 29
3
R2.4 xyplot + panel.number problem
Hi all;
I'm trying to display a 2 panel plot for the Puromycin data from R
with 2 different non-linear models fitted to each group. The problem
is that as far as I know panel.number doesn't work in the latest
version of R. Can anyone give a hint how to solve this?
Here is the code that I used before and now doesn't work
xyplot(rate ~conc| state,Purom...
2011 Apr 20
1
How can I 'predict' from an nls model with a fit specified for separate groups?
...xample on p 111 in 'Nonlinear Regression with R' by Ritz &
Streibig, I have been fitting nls models using square brackets with the
grouping variable inside. In their book is this example, in which
'state' is a factor indicating whether a treatment has been used or not:
> Puromycin.m1 <- nls(rate ~ Vm[state] *
+ conc/(K[state] + conc), data = Puromycin,
+ start = list(K = c(0.1, 0.1),
+ Vm = c(200, 200)))
What I cannot figure out is how to specify the value of the grouping
variable in a 'predict' statement. In my own example, I can only seem to
get the predictio...
2009 Nov 17
1
Define lm/glm object without evaluating them
...g and then only fit the models later 'when data arrives'. To be specific, I would like make a specification like
m1 <- lm(rate~conc)
m2 <- lm(rate~I(conc^2))
and then later I want to 'put data into' the objects and evaluate (fit the model), e.g. something like
update(m1, data=Puromycin)
update(m2, data=Puromycin)
The 'closest' I can get to what I want is
1) Specification:
m.list <-expression(lm(rate~conc), lm(rate~I(conc^2)))
2) Update with data:
m.list2 <- lapply(m.list, function(m) {m$data=Puromycin; return(m)})
3) Now, evaluate:
lapply(m.list2, eval)
Can anyone...
2003 Oct 28
2
Confidence ellipse for correlation
...e ellipse for the correlation coefficient. Since I
generally like R so much better, I would like to reproduce this in R. I've
been playing with the ellipse package. In order to have the points and the
ellipse on the same graph I've done the following.
(Load ellipse package...)
> data(Puromycin)
> attach(Puromycin)
> my<-mean(rate)
> mx<-mean(conc)
> sdy<-sd(rate)
> sdx<-sd(conc)
> r<-cor(conc,rate)
> plot(ellipse(r,scale=c(sdx,sdy),centre=c(mx,my)),type='l')
> points(conc,rate)
1) Is my use of 'scale' and 'centre' theoretica...
2008 Nov 03
2
standard errors for predict.nls?
Dear all,
Is there a way to retrieve standard errors from nls models? The help page tells me that arguments
such as se.fit are ignored...
Many thanks and best wishes
Christoph
--
Dr. rer.nat. Christoph Scherber
University of Goettingen
DNPW, Agroecology
Waldweg 26
D-37073 Goettingen
Germany
phone +49 (0)551 39 8807
fax +49 (0)551 39 8806
Homepage http://www.gwdg.de/~cscherb1
2003 Oct 30
2
'nls' and its arguments
...ments, i.e. I defined it
as f(...) {<body>}. (Ok, that's not actually impotant).
2) Second, I would NOT like to supply every parameter in the formula.
To illustrate this, let's look at the last example of 'nls' help
page:
## weighted nonlinear regression
data(Puromycin)
Treated <- Puromycin[Puromycin$state == "treated", ]
weighted.MM <- function(resp, conc, Vm, K)
{
## Purpose: exactly as white book p.451 -- RHS for nls()
## Weighted version of Michaelis-Menten model
## -----------------------------------------...
2004 May 21
1
Buglet/omission in nls package (PR#6901)
Dear all,
I noticed the following under R 1.8.1 (when nls was still a separate
package) but the same problem occurs under R 1.9.0 (where most (all?)
of nls is now in the stats package):
> data(Puromycin)
> fm <- nls(rate~SSmicmen(conc,b0,b1), Puromycin, subset = state=="treated")
> coef(summary(fm))
NULL
The problem seems to be that summary.nls uses the name "parameters"
instead of the name "coefficients" for the matrix with the estimates,
standard errors, t...
2005 Jul 11
2
Weighted nls
Dear R Community,
I am attempting to perform a weighted non-linear least squares fit. It has already been noted that the weights option is not yet implemented for the nls function, but no one seems to offer any suggestions for getting around this problem. I am still curious if a) anyone has code they have written which includes a weight options for nls, or b) if there is another model which
2004 Nov 08
2
Nonlinear weighted least squares estimation
Hi there,
I'm trying to fit a growth curve to some data and need to use a weighted least squares estimator to account for heteroscedasticity in the data. A weights argument is available in nls that would appear to be appropriate for this purpose, but it is listed as 'not yet implemented'. Is there another package which could implement this procedure?
Regards,
Robert Brown
2007 Jun 07
2
Nonlinear Regression
Hello
I followed the example in page 59, chapter 11 of the 'Introduction to R'
manual. I entered my own x,y data. I used the least squares. My function has
5 parameters: p[1], p[2], p[3], p[4], p[5]. I plotted the x-y data. Then I
used lines(spline(xfit,yfit)) to overlay best curves on the data while
changing the parameters. My question is how do I calculate the residual sum
of squares.
2004 Feb 02
1
Robust nonlinear regression - sin(x)/x?
...an error:
>
> x <- seq(1,10,0.1)
> y <- sin(x)/x
> plot(x,y)
> z <- jitter(y,amount=0.1)
> plot(x,z)
> df <- as.data.frame(cbind(x,z))
> nf <- nls(z ~ a*sin(x)/b*x, data=df,
> start=list(a=0.8,b=0.9), trace = TRUE)
>
> I have followed the Puromycin sample which works fine:
> Pur.wt <- nls(rate ~ (Vm * conc)/(K + conc), data = Treated,
> start = list(Vm = 200, K = 0.1), trace = TRUE)
>
> Do I make some mistake or is it not possible to fit sin(x)/x?
>
> Thank you in advance
> Best regards
> Christian
&...
2010 Jan 29
1
Step function
Hi All,
Does the step function work in this model? I tried to run the
following model but no result obtained. The computer is hanging and I
killed the job several times. Below is the code.
library(survival)
m.fit=clogit(y~x1+x2+x3+x4, data=ftest)
summary(m.fit)
final<- step(m.fit)
Thanks in advance.
2005 Feb 02
4
(no subject)
...tercountry Life-Cycle Savings Data
Loblolly Growth of Loblolly pine trees
Nile Flow of the River Nile
Orange Growth of orange trees
OrchardSprays Potency of Orchard Sprays
PlantGrowth Results from an Experiment on Plant Growth
Puromycin Reaction velocity of an enzymatic reaction
Seatbelts Road Casualties in Great Britain 1969-84
Theoph Pharmacokinetics of theophylline
Titanic Survival of passengers on the Titanic
ToothGrowth The Effect of Vitamin C on Tooth G...
2003 Nov 19
11
Windows R 1.8.0 hangs when Mem Usage >1.8GB
I have a loop that increases the size of an object after each iteration. When the Windows Task Manager shows "Mem Usage" about 1.8GB, the Rgui.exe process no longer responds.
I use:
"C:\Program Files\R\rw1080\bin\Rgui.exe" --max-mem-size=4000M --min-vsize=10M --max-vsize=3000M --min-nsize=500k --max-nsize=1000M
I have a dual Xeon 2.8GHz processor box with 4GB of memory and
2002 Jul 11
1
dyn.load tcl/tk (PR#1774)
...html latex example
NLSstClosestX text html latex example
NLSstLfAsymptote text html latex example
NLSstRtAsymptote text html latex example
Orange text html latex example
Puromycin text html latex example
SSasymp text html latex example
SSasympOff text html latex example
SSasympOrig text html latex example
SSbiexp tex...
2000 Feb 17
2
Installation of rpm file on Suse Linux 6.2 (PR#449)
...ibrary/nls/data/Loblolly.R action: create
D: file: /usr/local/lib/R/library/nls/data/Orange.R action: create
D: file: /usr/local/lib/R/library/nls/data/Orthodont.R action: create
D: file: /usr/local/lib/R/library/nls/data/Pixel.R action: create
D: file: /usr/local/lib/R/library/nls/data/Puromycin.R action: create
D: file: /usr/local/lib/R/library/nls/data/Theoph.R action: create
D: file: /usr/local/lib/R/library/nls/help action: create
D: file: /usr/local/lib/R/library/nls/help/00Titles action: create
D: file: /usr/local/lib/R/library/nls/help/AnIndex action: create
D: file:...