[R] Calling a procedure

[Steven Yen]

Thanks to all for educating me about procedures and argument. Those were 
very helpful!!

On 2020/9/21 上午 12:26, Bert Gunter wrote:
> Argument passing is fundamental, even more so when you write your own 
> functions, which any half-serious R user will want to do. What has 
> heretofore been discussed in this thread is not the whole story (e.g. 
> there are ... arguments and functions as binary operators, among other 
> things).  See section 10 of the "Introduction to R" document that 
> ships with R or any other decent R tutorial of your choice. The R 
> language definition is the definitive reference (section 4 especially 
> for this).
>
> All imo of course.
>
> Bert Gunter
>
> "The trouble with having an open mind is that people keep coming along 
> and sticking things into it."
> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>
>
> On Sun, Sep 20, 2020 at 8:57 AM Mark Leeds <markleeds2 using gmail.com 
> <mailto:markleeds2 using gmail.com>> wrote:
>
>     Hi Steven: Rui's detailed explanation was great.  The way I think
>     of it is,
>     if you don't
>     want to send the  variables in with the same  order as the formal
>     arguments, then you
>     better  name them as you send them in.
>
>
>
>
>
>     On Sun, Sep 20, 2020 at 7:23 AM Steven Yen <styen using ntu.edu.tw
>     <mailto:styen using ntu.edu.tw>> wrote:
>
>     > Thanks. So, to be safe, always a good idea to give the argument,
>     e.g.,
>     > q=1.96, log.p=FALSE, skipping mean=0 and sd=1 if not needed. Thanks.
>     >
>     > pnorm(q=1.96, log.p = FALSE)
>     >
>     > On 2020/9/20 下午 06:36, Rui Barradas wrote:
>     > > Hello,
>     > >
>     > > You are making a confusion between
>     > >
>     > > 1. the formal argument log.p
>     > > 2. the variable log.p
>     > >
>     > > In the function body, log.p is a variable that exists in the
>     > > function's frame, not the formal argument of pnorm.
>     > > The first and the 3rd calls that follow output the same value.
>     > >
>     > > try(x = 1.2, log.p = TRUE)$a
>     > > try(x = 1.2, log.p = TRUE)$b
>     > > try(x = 1.2, 1)$a
>     > >
>     > > This is because in the function
>     > >
>     > >   a<-pnorm(x,log.p)       # first call
>     > >
>     > > passes log.p as the *second* argument, not as a value for pnorm's
>     > > formal argument log.p. Unless when named, the arguments are
>     passed in
>     > > the order they appear in the function's definition:
>     > >
>     > > pnorm(q, mean = 0, sd = 1, lower.tail = TRUE, log.p = FALSE)
>     > >
>     > > and that becomes
>     > >
>     > >   a<-pnorm(x,TRUE)       # first call
>     > >   a<-pnorm(x,1)          # first call, coerced to numeric.
>     > >
>     > >
>     > > Let me give another example. In the function that follows the
>     default
>     > > is z = FALSE.
>     > >
>     > > In the first call the name z is not the name of the argument,
>     it's the
>     > > name of a variable that exists in the .GlobalEnv.
>     > >
>     > > In the second call, z = z assign the formal argument z the
>     value of
>     > > the variable z.
>     > >
>     > >
>     > > f <- function(x, y = 0, z = FALSE){
>     > >   a <- x
>     > >   b <- y
>     > >   d <- z
>     > >   list(a = a, b = b, d = d)
>     > > }
>     > > z <- 2
>     > > f(1, z)
>     > > f(1, z = z)
>     > >
>     > >
>     > > Hope this helps,
>     > >
>     > > Rui Barradas
>     > >
>     > > Às 11:11 de 20/09/20, Steven Yen escreveu:
>     > >> Can someone tell me a proper call to a procedure, in this case,
>     > >> pnorm. In what follows, I had expected a = b, but they are
>     not equal.
>     > >> What are wrong with first call and second call? Thank you!
>     > >>
>     > >> try<-function(x,log.p=FALSE){
>     > >> a<-pnorm(x,log.p)       # first call
>     > >> b<-pnorm(x,log.p=log.p) # second call
>     > >> list(a=a,b=b)
>     > >> }
>     > >>
>     > >> try(x=1.2,log.p=TRUE)$a
>     > >> try(x=1.2,log.p=TRUE)$b
>     > >>
>     > >> ______________________________________________
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>     > >> and provide commented, minimal, self-contained, reproducible
>     code.
>     >
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>     >
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>     > and provide commented, minimal, self-contained, reproducible code.
>     >
>
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>
>     ______________________________________________
>     R-help using r-project.org <mailto:R-help using r-project.org> mailing list --
>     To UNSUBSCRIBE and more, see
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>     and provide commented, minimal, self-contained, reproducible code.
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