[R-sig-teaching] count the number of argument of a function

[Steven Stoline]

Dear Michael:

Thank you very much for your quick reply.

Just one more thing. Assume we have these three data sets (vectors), but
could be 4, 5  or more data sets.

x1<-c(1,2,3,4,5)
x2<-c(11,22,33,44,55)
x3<-c(111,222,333,444,555)


Inside the same fumction I do need to use the cbind() function to cbind
these m (m could be 2, 3, 4, or any numbers) data sets. This what I trired,
but it did not work.

f <- function(x1,x2,x3){
        m<-length(formals(sys.function()))

print(m)

    data<-cbind(x1,x2,...,xm)                                   #### I need
some help with this part

print(data)

}

f(x1,x2,x3)



with thanks
steve



On Tue, Oct 20, 2015 at 3:51 PM, Michael Weylandt <
michael.weylandt at gmail.com> wrote:

> On Tue, Oct 20, 2015 at 2:45 PM, Steven Stoline <sstoline at gmail.com>
> wrote:
>
>> Dear All:
>>
>> I am wondering whether there is a way to read and assign the number of
>> arguments of a function inside this function.
>>
>>
>> ### For example
>>
>> fun<-function(x1,x2,x3,...){
>>
>> m<- number of arguments
>>
>> }
>>
>> ### e.g.
>>
>> fun<-function(x1,x2,x3){
>>
>> m<- number of arguments
>>
>> ### m =3 in this case
>>
>> }
>>
>> ### e.g.
>>
>> fun<-function(x1,x2,x3,y1,z1,z2){
>>
>> m<- number of arguments
>>
>> ### m =6 in this case
>>
>> }
>>
>
>
> It's not entirely kosher, but
>
> length(formals(sys.function()))
>
> will work.
>
> f <- function(a, b,c, d, e, f){
>     length(formals(sys.function()))
> }
>
> f() ## 6
>



-- 
Steven M. Stoline
1123 Forest Avenue
Portland, ME 04112
sstoline at gmail.com

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