[R] Trying to learn how to write an "advanced" function

[Rasmus Liland]

On 2023-03-16 12:11 +0000, Sorkin, John wrote:
> (1) can someone point me to an 
> explanation of match.call or match 
> that can be understood by the 
> uninitiated? 

Dear John,

the man page ?match tells us that match 
matches the first vector against the 
second, and returns a vector of indecies 
the same length as the first, e.g.

	> match(c("formula", "data", "subset", "weights", "na.action", "offset"), c("Maryland", "formula", "data", "subset", "weights", "na.action", "offset", "Sorkin", "subset"), 0L)
	[1] 2 3 4 5 6 7

perhaps a bad answer ... 

> (2) can someone point me to a document 
> that will help me learn how to write 
> an "advanced" function?

Perhaps the background here is looking 
at the lm function as a basis for 
writing something more advanced, then 
the exercise becomes looking at 
dput(lm), understanding every line by 
looking up all the functions you do not 
understand in the man pages e.g. ?match.  
Remember, you can search for things 
inside R by using double questionmark, 
??match, finding versions of match 
existing inside other installed 
packages, e.g.  raster::match and 
posterior::match, perhaps this exercise 
becomes writing ones own version of lm 
inside ones own package?

Best,
Rasmus