[R] error in exists.....

[akshay kulkarni]

Dear Bert,
                   Yeah, it's working....Sometimes (only sometimes) I feel that I am troubling this list with very simple questions the answer to which I always happen to find myself a little after...any solutions for that (you seem to be an omniscient person)!?

Thanking you,
Yours sincerely,
AKSHAY M KULKARNI
________________________________
From: Bert Gunter <bgunter.4567 using gmail.com>
Sent: Tuesday, December 27, 2022 11:39 PM
To: akshay kulkarni <akshay_e4 using hotmail.com>
Cc: Sarah Goslee <sarah.goslee using gmail.com>; R help Mailing list <r-help using r-project.org>
Subject: Re: [R] error in exists.....

You are confused about the list hierarchy. Perhaps this will explain:
> i <- 1
>  E <- new.env()
>   E$L <- list()  ## L is an empty list in E
>   i <- 1
>    E$L[[i]]$T1A1 <- Sys.time()
Error in `*tmp*`[[i]] : subscript out of bounds
## L is empty, so L[[1]] does not exist; is not a list;
## cannot have a value assigned to a component
## The following works:
## Create an empty list as a sublist of L
>  E$L[[1]] <- list()
## Now create and assign to a component of the empty list
>  E$L[[i]]$T1A1 <- Sys.time()
> E$L ## a list
[[1]]  ## whose first component is a list
[[1]]$T1A1 ## T1A1 named component of L[[1]]
[1] "2022-12-27 10:00:10 PST"

ergo, no conundra... (assuming I've understood you correctly)

Cheers,
Bert

On Tue, Dec 27, 2022 at 9:57 AM akshay kulkarni <akshay_e4 using hotmail.com> wrote:
>
> Dear Sarah,
>                      I had this also before the assignment of Sys.time():
>
> >     E$L[[i]] <- i
>
> After assignment of Sys.time():
>
> > E$L
> [[1]]
> [[1]][[1]]
> [1] 1
>
> [[1]]$T1A1
> [1] "2022-12-27 22:40:02 IST"
>
> regrets for not sharing this ......Can you reproduce it now?
>
> Thanking you,
> Yours sincerely,
> AKSHAY M KULKARNI
> ________________________________
> From: Sarah Goslee <sarah.goslee using gmail.com>
> Sent: Tuesday, December 27, 2022 11:20 PM
> To: akshay kulkarni <akshay_e4 using hotmail.com>
> Cc: R help Mailing list <r-help using r-project.org>
> Subject: Re: [R] error in exists.....
>
> Hi,
>
> I can't create the desired object using the code you provided, but if
> I create it in two steps so that E$L[[i]]$T1A1 does exist, exist()
> returns TRUE.
>
> E <- new.env()
> E$L <- list()
> i <- 1
> E$L[[i]]$T1A1 <- Sys.time()
>
> # returns: Error in `*tmp*`[[i]] : subscript out of bounds
>
> E$L[[i]] <- list()
> E$L[[i]]$T1A1 <- Sys.time()
>
>
> exists("T1A1", where = E$L[[i]])
> # returns: [1] TRUE
>
>
> > str(E$L)
> List of 1
>  $ :List of 1
>   ..$ T1A1: POSIXct[1:1], format: "2022-12-27 12:47:26"
>
> Sarah
>
> On Tue, Dec 27, 2022 at 12:36 PM akshay kulkarni <akshay_e4 using hotmail.com> wrote:
> >
> > Dear members,
> >                              I have the following code:
> > >  E <- new.env()
> > >  E$L <- list()
> > >  i <- 1
> > >   E$L[[i]]$T1A1 <- Sys.time()
> > > exists("T1A1", where = E$L[[i]])
> > Error in list2env(list(1, T1A1 = 1672161002.38743), NULL, <environment>) :
> >   attempt to use zero-length variable name
> >
> > I want the output of the exists() function to be TRUE. In any case:
> >
> > > E$L[[1]]$T1A1
> > [1] "2022-12-27 22:40:02 IST"
> >
> > Please help me solve this conundrum....
> >
> > Thanking you,
> > Yours sincerely,
> > AKSHAY M KULKARNI
> >
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
>
>
> --
> Sarah Goslee (she/her)
> http://www.numberwright.com
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

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