Hello,
To access list elements you need `[[`, like this:
summ.list[[2]]$coefficients
Or Use the extractor function,
coef(summ.list[[2]])
Rui Barradas
Em 28-09-2012 07:23, Krunal Nanavati escreveu:
Hi Rui,
Excellent!! This is what I was looking for. Thanks for the help.
So, now I have stored the result of the 10 regressions in "summ.list
<- lapply(lm.list2, summary)"
And now once I enter " sum.list "....it gives me the output for all
the 10 regressions...
I wanted to access a beta coefficient of one of the regressions....say
"Price2+Media1+Trend+Seasonality"...the result of which is stored in"
sum.list[2] "
I entered the below statement for accessing the Beta coefficient for
Price2...
summ.list[2]$coefficients[2]
NULL
But this is giving me " NULL " as the output...
What I am looking for, is to access a beta value of a particular variable
from a particular regression output and use it for further analysis.
Can you please help me out with this. Greatly appreciate, you guys
efforts.
Thanks & Regards,
Krunal Nanavati
9769-919198
-----Original Message-----
From: Rui Barradas [mailto:ruipbarra...@sapo.pt]
Sent: 27 September 2012 21:55
To: Krunal Nanavati
Cc: David Winsemius; r-help@r-project.org
Subject: Re: [R] Running different Regressions using for loops
Hello,
Inline.
Em 27-09-2012 13:52, Krunal Nanavati escreveu:
Hi,
Thanks for all your help. I am stuck again, but with a new problem, on
similar lines.
I have taken the problem to the next step now...i have now added 2 "for"
loops... 1 for the Price variable...and another for the Media variable
I have taken 5 price variables...and 2 media variables with the "trend
and seasonality"(appearing in all of them)....so in all there will be
10 regression to run now
Price 1, Media 1
Price 1, Media 2
Price 2, Media 1'
Price 2, Media 2
...and so on
I have built up a code for it...
tryout=read.table("C:\\Users\\Krunal\\Desktop\\R
tryout.csv",header=T,sep=",")
cnames <- names(tryout)
price <- cnames[grep("Price", cnames)] media <- cnames[grep("Media",
cnames)] resp <- cnames[1] regr <- cnames[7:8] lm.list <-
vector("list", 10) for(i in 1:5)
+ {
+ regress <- paste(price[i], paste(regr, collapse = "+"), sep = "+")
+ for(j in 1:2) {
+ regress1 <- paste(media[j],regress,sep="+") fmla <- paste(resp,
+ regress1, sep = "~") lm.list[[i]] <- lm(as.formula(fmla), data =
+ tryout) } }
summ.list <- lapply(lm.list, summary) summ.list
But it is only running...5 regressions...only Media 1 along with the 5
Price variables & Trend & Seasonality is regressed on Volume...giving
only
5 outputs
I feel there is something wrong with the " lm.list[[i]] <-
lm(as.formula(fmla), data = tryout)" statement.
No, I don't think so. If it's giving you only 5 outputs the error is
probably in the fmla construction. Put print statements to see the results
of those paste() instructions.
Supposing your data.frame is now called tryout2,
price <- paste("Price", 1:5, sep = "")
media <- paste("Media", 1:2, sep = "")
pricemedia <- apply(expand.grid(price, media, stringsAsFactors = FALSE),
1, paste, collapse="+")
response <- "Volume"
trendseason <- "Trend+Seasonality" # do this only once
lm.list2 <- list()
for(i in seq_along(pricemedia)){
regr <- paste(pricemedia[i], trendseason, sep = "+")
fmla <- paste(response, regr, sep = "~")
lm.list2[[i]] <- lm(as.formula(fmla), data = tryout2) }
The trick is to use ?expand.grid
Hope this helps,
Rui Barradas
I am not sure about its
placement...whether it should be in loop 2 or in loop 1
Can you please help me out??
Thanks & Regards,
Krunal Nanavati
9769-919198
-----Original Message-----
From: Rui Barradas [mailto:ruipbarra...@sapo.pt]
Sent: 27 September 2012 16:22
To: David Winsemius
Cc: Krunal Nanavati; r-help@r-project.org
Subject: Re: [R] Running different Regressions using for loops
Hello,
Just to add that you can also
lapply(lm.list, coef)
with a different output.
Rui Barradas
Em 27-09-2012 09:24, David Winsemius escreveu:
On Sep 26, 2012, at 10:31 PM, Krunal Nanavati wrote:
Dear Rui,
Thanks for your time.
I have a question though, when I run the 5 regression, whose outputs
are stored in "lm.list[i]", I only get the coefficients for the
Intercept, Price, Trend & Seasonality as below
lm.list[1]
[[1]]
Call:
lm(formula = as.formula(fmla), data = tryout)
Coefficients:
(Intercept) Price4 Trend Seasonality
9923123 -2606826 64616 551392
summ.list <- lapply(lm.list, summary) coef.list <- lapply(summ.list,
coef) coef.list
I am also looking out for t stats and p value and R squared.
For the r.squared
rsq.vec <- sapply(summ.list, "$", "r.squared") adj.rsq <-
sapply(summ.list, "$", "adj.r.squared")
Do you know,
how can I get all these statistics. Also, why is " as.formula " used
in the lm function. It should work without that as well, right?
No.
Can you please tell me, why the code that I had written, does not
work with R. I thought it should work perfectly.
In R there is a difference between expression objects and character
objects.
Thanks & Regards,
Krunal Nanavati
9769-919198
*From:* Rui Barradas [mailto:ruipbarra...@sapo.pt]
*Sent:* 26 September 2012 17:13
*To:* Krunal Nanavati
*Cc:* r-help@r-project.org
*Subject:* Re: [R] Running different Regressions using for loops
Hello,
Try the following.
#cnames <- names(tryout) # in your code, use this one cnames <-
c("Volume", "Price1", "Price2", "Price3", "Price4", "Price5",
"Trend", "Seasonaliy")
price <- cnames[grep("Price", cnames)] resp <- cnames[1] regr <-
cnames[7:8]
#lm.list <- vector("list", 5)
for(i in 1:5){
regress <- paste(price[i], paste(regr, collapse = "+"), sep =
"+")
fmla <- paste(resp, regress, sep = "~")
print(fmla)
#lm.list[[i]] <- lm(as.formula(fmla), data = tryout) }
Hope this helps,
Rui Barradas
Em 26-09-2012 08:08, Krunal Nanavati escreveu:
Hi,
I am trying to run many different regressions using a FOR Loop.
The input data that is read into R has the following variables
. Volume
. Price2
. Price3
. Price4
. Price5
. Trend
. Seasonality
I want to run 5 regressions, with the Volume as an dependent
variable and
Price, Trend & Seasonality as independent variables. I have read the
above
mentioned variables in a variable called "tryout"
I am entering the following syntax in R
for(i in 1:5)
+ {
+ result[i]=lm(Volume~Price[i]+Trend+Seasonaliy,data=tryout)
+ summary(result[i])
+ }
After running these lines.I am getting the following error message
Error in eval(expr, envir, enclos) : object 'Price' not found
Can someone help me out with this error message. Appreciate for your
time
and consideration.
[[alternative HTML version deleted]]
David Winsemius, MD
Alameda, CA, USA
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