[R] For Loop

Duncan Murdoch murdoch@dunc@n @end|ng |rom gm@||@com
Sun Sep 23 22:10:57 CEST 2018

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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