Calling a procedure

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 at gmail.com 
<mailto:markleeds2 at 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 at ntu.edu.tw
    <mailto:styen at 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 ?? 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
    > >
    > > ?s 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
    > >>
    > >> ______________________________________________
    > >> R-help at r-project.org <mailto:R-help at r-project.org> mailing

    list -- To UNSUBSCRIBE and more, see

    > >> https://stat.ethz.ch/mailman/listinfo/r-help
    > >> PLEASE do read the posting guide
    > >> http://www.R-project.org/posting-guide.html

    code.

    >
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    >
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