[R] For Loop

[Duncan Murdoch]

On 23/09/2018 3:31 PM, Jeff Newmiller wrote:

[lots of good stuff deleted]

> Vectorize is
> syntactic sugar with a performance penalty.

[More deletions.]

I would say Vectorize isn't just "syntactic sugar".  When I use that 
term, I mean something that looks nice but is functionally equivalent.

However, Vectorize() really does something useful:  some functions (e.g. 
outer()) take other functions as arguments, but they assume the argument 
is a vectorized function.  If it is not, they fail, or generate garbage 
results.  Vectorize() is designed to modify the interface to a function 
so it acts as if it is vectorized.

The "performance penalty" part of your statement is true.  It will 
generally save some computing cycles to write a new function using a for 
loop instead of using Vectorize().  But that may waste some programmer time.

Duncan Murdoch
(writing as one of the authors of Vectorize())

P.S. I'd give an example of syntactic sugar, but I don't want to bruise 
some other author's feelings :-).