On 18/01/2012 1:51 PM, R. Michael Weylandt wrote:
Consider this example:
power<- function(n){
function(x) x^n
} # Note that this function returns a function!
One bit of advice that may matter sometime: you should call force(n) to
make sure it is evaluated before creating the new function. Otherwise
you get embarrassing results like this:
> n <- 3
> cube <- power(n)
> n <- 2
> cube(2)
[1] 4
Due to lazy evaluation, the n isn't evaluated until after it got changed
to 2. This version is safe:
power<- function(n){
force(n)
function(x) x^n
} # Note that this function returns a function!
Duncan Murdoch
cube<- power(3)
cube(2) # gives 8
That make sense?
Michael
On Wed, Jan 18, 2012 at 1:30 PM, statguy<marti...@mail.com> wrote:
> I would like to know if it is possible to make a function that defines a
> variable in another function without setting that variable globally?
>
> I would i.e. be able to define a variables value inside a function ("one
> level above) which another function makes use of, without setting this
> variable globally.
>
> I have provided this very simple illustrating example.
>
> test1=function(x)
> {
> x+y
> }
> test2=function(y1)
> {
> y=y1
> test1(2,y1)
> }
>
> Running the second function results in an error:
>> test2(1)
> Error in test1(2) : object 'y' not found
>
> I see 2 possible solutions to this, but neither of them is preferred in my
> more complex situation:
>
> 1. Setting y<<-y_1 globally in test2-function
> 2. making test1 a function of both x and y.
>
> Is there any other way to do this except from the 2 above? I hope someone
> can help me with this.
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/How-to-define-a-variable-in-a-function-that-another-function-uses-without-using-global-variables-tp4307604p4307604.html
> Sent from the R help mailing list archive at Nabble.com.
>
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______________________________________________
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and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
