why does this simple example NOT work?

[Martin Ivanov]

 Hello,

I want to create and save objects in a loop, but this is precluded by the following obstacle:
this part of the script fails to work:

assign(x=paste("a", 1, sep=""), value=1);
save(paste("a", 1, sep=""), file=paste(paste("a", 1, sep=""), ".RData", sep=""))

Do you know any workaround? I am already out of ideas.

Best regards,

Martin

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[Berend Hasselman]

Martin Ivanov wrote

Hello,

I want to create and save objects in a loop, but this is precluded by the following obstacle:
this part of the script fails to work:

assign(x=paste("a", 1, sep=""), value=1);
save(paste("a", 1, sep=""), file=paste(paste("a", 1, sep=""), ".RData", sep=""))

Do you know any workaround? I am already out of ideas.

You haven't given the error message R provides.
Carefully read the documentation of save.

save(list=paste("a", 1, sep=""), file=paste(paste("a", 1, sep=""), ".RData", sep=""))

This "works" for for me.

Berend

[Duncan Murdoch-2]

On 12-07-20 2:50 AM, Martin Ivanov wrote:
>   Hello,
>
> I want to create and save objects in a loop, but this is precluded by the following obstacle:
> this part of the script fails to work:
>
> assign(x=paste("a", 1, sep=""), value=1);
> save(paste("a", 1, sep=""), file=paste(paste("a", 1, sep=""), ".RData", sep=""))

paste("a", 1, sep="") is equivalent to "a1".  So you are saving the
string "a1" to the file "a1.RData".  You presumably want to save the
value of the variable a1, not that string.  (Though you didn't say that.
  It's helpful to describe what you don't like, don't just say it "fails
to work".)

If you have the name of a variable in a string, you can use get() to get
the value.  So I think this code would do what you want:

name <- paste0("a", 1)
assign(x=name, value=1)
save(get(name), file=paste0(name, ".RData"))

(If you don't have the paste0 function, you should upgrade to the
current R version.)

Duncan Murdoch

>
> Do you know any workaround? I am already out of ideas.
>
> Best regards,
>
> Martin
>
> ______________________________________________
> [hidden email] mailing list
> 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.
>

______________________________________________
[hidden email] mailing list
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.

[Berend Hasselman]

Duncan Murdoch-2 wrote

On 12-07-20 2:50 AM, Martin Ivanov wrote:
>   Hello,
>
> I want to create and save objects in a loop, but this is precluded by the following obstacle:
> this part of the script fails to work:
>
> assign(x=paste("a", 1, sep=""), value=1);
> save(paste("a", 1, sep=""), file=paste(paste("a", 1, sep=""), ".RData", sep=""))

paste("a", 1, sep="") is equivalent to "a1".  So you are saving the
string "a1" to the file "a1.RData".  You presumably want to save the
value of the variable a1, not that string.  (Though you didn't say that.
  It's helpful to describe what you don't like, don't just say it "fails
to work".)

If you have the name of a variable in a string, you can use get() to get
the value.  So I think this code would do what you want:

name <- paste0("a", 1)
assign(x=name, value=1)
save(get(name), file=paste0(name, ".RData"))

I tried that in R2.15.1 and got the error message:

Error in save(get(name), file = paste0(name, ".RData")) :
  object ‘get(name)’ not found

Using the list argument "worked":

save(list=name, file=paste0(name, ".RData"))

Berend