R help - Oct 2009 - external variable by inside-function routines modifications

Dear all,

  could you please advice whether it is possible somehow to modify an
external (from the point of some function view) variable by some
function-internal operators. For example
> var=1
> foo<-function(var){var=var+1}
> foo(var)
> var
[1] 1

but the goal is to get the var equal to 2 in this specific case.

Thanks!
-- 
View this message in context:
http://www.nabble.com/external-variable-by-inside-function-routines-modifications-tp25803308p25803308.html
Sent from the R help mailing list archive at Nabble.com.

See assign, you can use '<<-' assignment:

foo <- function(var) var <<- var + 1

On Thu, Oct 8, 2009 at 2:14 PM, devol <sunduck at gmail.com>
wrote:
>
> Dear all,
>
> ?could you please advice whether it is possible somehow to modify an
> external (from the point of some function view) variable by some
> function-internal operators. For example
>
>> var=1
>> foo<-function(var){var=var+1}
>> foo(var)
>> var
> [1] 1
>
> but the goal is to get the var equal to 2 in this specific case.
>
> Thanks!
> --
> View this message in context:
http://www.nabble.com/external-variable-by-inside-function-routines-modifications-tp25803308p25803308.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org 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.
>


-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O

Hi,

with assign,

foo <- function(var){
  assign("var", var+1, envir = .GlobalEnv)
}

var =1
foo(2)
var
# [1] 3

HTH,

baptiste



2009/10/8 devol <sunduck at gmail.com>:
>
> Dear all,
>
> ?could you please advice whether it is possible somehow to modify an
> external (from the point of some function view) variable by some
> function-internal operators. For example
>
>> var=1
>> foo<-function(var){var=var+1}
>> foo(var)
>> var
> [1] 1
>
> but the goal is to get the var equal to 2 in this specific case.
>
> Thanks!
> --
> View this message in context:
http://www.nabble.com/external-variable-by-inside-function-routines-modifications-tp25803308p25803308.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org 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.
>

On Oct 8, 2009, at 1:14 PM, devol wrote:
>
> Dear all,
>
>  could you please advice whether it is possible somehow to modify an
> external (from the point of some function view) variable by some
> function-internal operators. For example
>
>> var=1
>> foo<-function(var){var=var+1}
>> foo(var)
>> var
> [1] 1
Use functions the way they are designed to be used in R ... to return  
values:

 > var <- foo(var)
 > var
[1] 2
 >
>
> but the goal is to get the var equal to 2 in this specific case.
>
> Thanks!
> -- 
> View this message in context:
http://www.nabble.com/external-variable-by-inside-function-routines-modifications-tp25803308p25803308.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org 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.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT

devol wrote:
> 
> Dear all,
> 
>   could you please advice whether it is possible somehow to modify an
> external (from the point of some function view) variable by some
> function-internal operators. For example
> 
>> var=1
>> foo<-function(var){var=var+1}
>> foo(var)
>> var
> [1] 1
> 
> but the goal is to get the var equal to 2 in this specific case. Maybe it
> is possible to set the var as some kind of global type and then it will be
> returned from the function as I want it to see... 
> 
> Thanks!
> 
?"<<-" 

although this should be used sparingly.  See section 6  of
<http://www.burns-stat.com/pages/Tutor/R_inferno.pdf> ...
-- 
View this message in context:
http://www.nabble.com/modifications-of-out-of-the-function-variable-tp25803308p25803347.html
Sent from the R help mailing list archive at Nabble.com.