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:ruipbarradas at sapo.pt]
> *Sent:* 26 September 2012 17:13
> *To:* Krunal Nanavati
> *Cc:* r-help at 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