[R] persistant: Matlab->R

[Greg Snow]

It looks like the same process can be accomplished by using 'local' and
declaring the 'persistant' variables in a local scope, then the function
within that same scope, for example:

> inc <- local( { n <- 0; function(){n <<- n + 1; return(n)} } )
> inc
function(){n <<- n + 1; return(n)}
<environment: 0x09a8fee0>
> inc()
[1] 1
> inc()
[1] 2
> inc()
[1] 3
> inc()
[1] 4

Using local in R is a little more flexible in that you can have
variables that are shared between multiple functions, but not easily
accessable to the world at large:

> n <- 5
> incdec <- local( {n <- 0;
+ list(inc=function(){ n <<- n+1; return(n) },
+ dec=function(){ n <<- n-1; return(n) }
+ )})
> incdec$inc()
[1] 1
> incdec$inc()
[1] 2
> incdec$inc()
[1] 3
> incdec$dec()
[1] 2
> incdec$dec()
[1] 1
> incdec$inc()
[1] 2
> n
[5]


Hope this helps,


-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
 

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Bernard Gregory
Sent: Thursday, December 14, 2006 11:14 AM
To: r-help at stat.math.ethz.ch
Subject: [R] persistant: Matlab->R

Dear list members,

Could anyone tell me if there is an equivalent of the Matlab declaration
'persistant' in R?

Thank you very much,

Bernard Gregorry.
(Matlaber converted to R).

 		
---------------------------------

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