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

From: GuangXing <guangxing_at_ict.ac.cn>
Date: Wed 07 Dec 2005 - 12:03:41 EST


I think "<-" is better than "=" in some cases.

>
>
>======= 2005-12-07 04:17:03 您在来信中写道:=======
>
>>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
>>
>>>
>>
>>______________________________________________
>>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
>
>= = = = = = = = = = = = = = = = = = = =
>
>
>
>
>
>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

        GuangXing
        guangxing@ict.ac.cn
          2005-12-07



______________________________________________

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 12:10:43 2005

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