[R] Printing upon calling a function

[Steven Yen]

No, sorry. Line 1 below did not print for me and I had to go around and 
do line 2 to print:

me.probit(obj)

v<-me.probit(obj); v

A puzzle.


On 2020/11/30 下午 07:00, Duncan Murdoch wrote:
> On 30/11/2020 5:41 a.m., Stefan Evert wrote:
>>
>>> On 30 Nov 2020, at 10:41, Steven Yen <styen using ntu.edu.tw> wrote:
>>>
>>> Thanks. I know, my point was on why I get something printed by 
>>> simply doing line 1 below and at other occasions had to do line 2.
>>>
>>> me.probit(obj)
>>
>> That means the return value of me.probit() has been marked as 
>> invisible, so it won't auto-print.  You have to use an explicit print
>>
>>     print(me.probit(obj))
>>
>> or use your work-around to convince R that you actually meant to 
>> print the output.
>>
>> If you dig through the full code of me.probit(), you'll probably find 
>> the function invisible() called somewhere.
>>
>
> I think you misread his post.  "me.probit(obj)" on its own *did* 
> print.  It was when he assigned it to a variable using "v <- 
> me.probit(obj)" that it didn't.  Assignments are almost always 
> invisible in R.
>
> The other thing that people sometimes find confusing is that 
> evaluating expressions that are visible are the top level doesn't make 
> them print when they are nested in a block of code.  Usually this 
> happens in a function, e.g. typing a number normally makes it visible, 
> but
>
> f <- function() {
>   1
>   2
> }
> f()
>
> doesn't print 1, it only prints 2, and that happens because 2 is the 
> return value of the function.
>
> Duncan Murdoch