[R] For Loop

[Bert Gunter]

"... I learned to say "try it and see" in many different ways. "

Version 2: *Never* parallelize your computations  .... except when you
should.

;-)

-- Bert



On Sun, Sep 23, 2018 at 1:20 PM Duncan Murdoch <murdoch.duncan using gmail.com>
wrote:

> On 23/09/2018 4:00 PM, Wensui Liu wrote:
> > Very insightful. Thanks, Duncan
> >
> > Based on your opinion, is there any benefit to use the parallelism in
> > the corporate computing environment where the size of data is far more
> > than million rows and there are multiple cores in the server.
>
> I would say "try it and see".  Sometimes it probably helps a lot,
> sometimes it's probably detrimental.
>
> Duncan Murdoch
>
> P.S. I last worked in a corporate computing environment 40 years ago
> when I was still wet behind the ears, so you'd probably want to ask
> someone else.  However, more recently I worked in an academic
> environment where I learned to say "try it and see" in many different
> ways.  You just got the basic one today.
>
>
> >
> > Actually the practice of going concurrency or not is more related to my
> > production tasks instead of something academic.
> >
> > Really appreciate your thoughts.
> >
> > On Sun, Sep 23, 2018 at 2:42 PM Duncan Murdoch <murdoch.duncan using gmail.com
> > <mailto:murdoch.duncan using gmail.com>> wrote:
> >
> >     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 :-).
> >
>
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