[R] Name assignment in for loop

[Bert Gunter]

... or let R do all the setup:

lmModels <- lapply(seq_len(nrow(dat2)) , FUN = etc. ## the last result
is returned as the list component

I never declare lists and use for() loops to fill them any more.

-- Bert

On Thu, Nov 1, 2012 at 2:51 PM, Peter Alspach
<Peter.Alspach at plantandfood.co.nz> wrote:
> Tena koe Toby
>
> Try creating a list and storing each model as an element of the list.  For example,
>
> lmModels <- vector('list', nrow(dat2))
> for (i in 1:nrow(dat2))
> {
>   lmModels[[i]] <- etc
> }
>
> Generally, I add a line after creating the list to name the elements and then address the list using these names as I find that less error prone and more informative.
>
> HTH ....
>
> Peter Alspach
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of nrm2010
> Sent: Friday, 2 November 2012 10:16 a.m.
> To: r-help at r-project.org
> Subject: [R] Name assignment in for loop
>
>
>
> Dear helpeRs-
>
> I'm using a for loop to create a series of models.
> I'm trying to assign a name to each model created, using the loop index.  The loop gets stuck at the name  of the model, giving the error "target of assignment expands to non-language object".  The linear model runs without error; only the name is problematic.
>
> Here is the current loop syntax.  The use of dat and dat2 is not an error.  I'm pulling data from 2 sources for the model.
>
> for (i in 1:dim(dat2)[[1]]) {
> assign("modelb",i) <- lm(log(dat$flux) ~ dat$Tsoil_flux, subset = dat$chamber == dat2$chamber[i] & dat$year == dat2$year[i] & dat$doy >= dat2$day1[i] & dat$doy <= dat2$day2[i]) dat2$coef[i] <- coef(assign("modelb",i, sep = ""))[[2]] dat2$Rsq[i] <- summary(assign("modelb",i, sep = ""))[[9]] }
>
> I have also tried
> assign("modelb",1:i) #following the ?assign example paste("modelb", i, sep = "") <- (...) assign(paste("modelb", i, sep = "")) <- (...) assign(paste("modelb", i, sep - ""), put linear model here) They all generate the same error message.
>
>
> dim(dat2)[[1]] is 29
>> dim(dat2)[[1]]
> [1] 29
>
>> class(dim(dat2)[[1]])
> [1] "integer"
>
> I have not included data because the problem is with the naming syntax;  no data are involved except for the number 29.
>
> Given this approach, rather than the sapply() approach, what is the correct  syntax for naming each model in the sequence?
>
> Thank you in advance.
>
> Toby Gass
>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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