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As
you noticed, I got the parenthesis in the wrong place. Another
correct way would be
t(coef(fit)[-1, ])
From: Peng Huang [mailto:huangp@musc.edu]
Hi Bill,
Thank you for your help. Since I want to perform a
series of regressions (in fact, I want to use lme instead of lm in my data
analysis, but my last email used lm for simplification)
[WNV] This is nearly always a bad idea when you are new to
the game because your perception of the nub of the problem may not be the
reality.
If
you would like to tell us the real problem perhaps we can offer you some useful
advice on how to solve it.
with the
same predictors, I would like to do all of them automatically instead of
manually by re-typing the dependent variable name each time. If we can do it
without loop, that will be great too.
When I ran your code, I got
different results from what I expected:
> mydata<-
data.frame(x1=1:10,
x2=(1:10)^2,
y1=2*(1:10) + (1:10)^2 +
rnorm(10),
y2=10*(1:10) + 3*(1:10)^2 + rnorm(10))
> mydata
x1
x2
y1 y2
1 1
1 2.753768 13.18116
2 2
4 9.362209 32.22619
3 3 9
13.504666 56.90398
4 4 16 23.968903
88.43677
5 5 25 36.091774 123.06842
6
6 36 48.724808 167.63793
7 7 49 63.295195
216.56807
8 8 64 79.249965 271.97426
9
9 81 99.071244 332.58214
10 10 100 120.344092
400.98084
> fit
<- lm(as.matrix(mydata[, 3:4]) ~ x1 + x2, mydata)
> output <- t(coef(fit)[, -1])
> output
[,1] [,2] [,3]
[1,] 1.111728
9.350874 3.060115
> output # this is what I
need:
x1 x2
mod1 2.102024
0.9910637
mod2 9.350874 3.0601154
Have I missed something?
Thanks!
Peng
Bill.Venables@csiro.au wrote:
Your
question "How [do I] write a loop to obtain the output?" implies that you
have already decided that you must need a loop. In fact you
don't. Here is how I would obtain your
output:
mydata<- data.frame(x1=1:10,
x2=(1:10)^2,
y1=2*(1:10) + (1:10)^2 +
rnorm(10),
y2=10*(1:10) +
3*(1:10)^2 + rnorm(10))
fit <- lm(as.matrix(mydata[, 3:4]) ~ x1 + x2,
mydata)
output
<- t(coef(fm)[, -1])
and
that's it.
Bill
V.
-----Original Message-----
From: s-news-owner@lists.biostat.wustl.edu
[mailto:s-news-owner@lists.biostat.wustl.edu] On Behalf Of Peng
Huang
Sent: Friday, 15
April 2005 1:27 PM
To: s-news@lists.biostat.wustl.edu
Subject: [S] loop over a series regression
models
Dear
All,
I have a
data frame that contains several dependent variables and independent
variables. I would like to save the regression coefficients after fitting
each dependent variables (with the same independent variables). How to
write a loop to do it automatically? For example, I
have
mydata<- data.frame(x1=1:10,
x2=(1:10)^2,
y1=2*c(1:10) + c(1:10)^2
+ rnorm(10),
y2=10*c(1:10) +
3*c(1:10)^2 + rnorm(10))
# I want
to perform the following
mod1<- summary(lm(y1~x1+x2,
data="">
mod2<- summary(lm(y2~x1+x2,
data="">
# then
save the coefficients:
output <- rbind(mod1, mod2)
Question:
how to write a loop to obtain the output?
Thank you for your
help!
Peng
Huang
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