Re: [R] R is GNU S, not C.... [was "how to get or store ....."]

From: ronggui <042045003_at_fudan.edu.cn>
Date: Wed 07 Dec 2005 - 11:51:30 EST

>From: vincent@7d4.com
>>
>> ronggui a 閏rit :
>>
>> > I think it is NOT just for historical reason.
>> > see the following example:
>> >
>> >>rm(x)
>> >>mean(x=1:10)
>> > [1] 5.5
>> >>x
>> > Error: object "x" not found
>>
>> x is an argument local to mean(),
>> did you expect another answer ?
>>
>> >>mean(x<-1:10)
>> > [1] 5.5
>> >>x
>> > [1] 1 2 3 4 5 6 7 8 9 10
>>
>> What is the goal of this "example" ?
>
>I believe it's to show why "<-" is to be preferred over "=" for
>assignment...

Yeah,I want to show "<-" is to be preferred. Sorry for not making it clearly.

>> Here with "<-",
>> (voluntary, or not, side effect)
>> the global variable x is, also, created.
>> Did the writer really want that ???
>
>Very much so, I believe.
>
>> I though there were other specific statements
>> especially intended for global assignment, eg "<<-".
>
>You need to distinguish assignment in function _call_ and assignment in
>function _definition_. They ain't the same.
>
>> If this example was intended to prove "<-"
>> is better than "="
>> ... I'm not really convinced !
>
>In that case, let's try another one (which is one big reason I stopped using
>"=" for assignment):
>
>
>> long.comp <- function(n) {
>+ Sys.sleep(n)
>+ n
>+ }
>> result = long.comp(30)
>> system.time(result = long.comp(30))
>Error in system.time(result = long.comp(30)) :
> unused argument(s) (result ...)
>> system.time(result <- long.comp(30))
>[1] 0.00 0.00 30.05 NA NA
>> str(result)
> num 30
>
>Cheers,
>Andy
>
>>
>
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2005-12-07



Deparment of Sociology
Fudan University

My new mail addres is ronggui.huang@gmail.com Blog:http://sociology.yculblog.com



R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Dec 07 11:58:19 2005

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