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Thread: "ocaml_beginners"::[] reading big file -> how to make it faster?




"ocaml_beginners"::[] reading big file -> how to make it faster?
user name
2006-06-04 23:42:08
On Sun, Jun 04, 2006 at 04:40:53PM -0700, Frederick Akalin
wrote:
> I've run into this before.  Basically, behind the
scenes, picture is an 
> array of pointers.  When you first call make_matrix,
you're passing in a 
> default value, but that means that every pointer in
picture points to 
> the *same* record with r=g=b=0, rather than each
pointer pointing to a 
> *different* record with r=g=b=0.
> 
> In the old code, you change each pointer in picture to
point to a 
> newly-created record, but in the new code you're
updating the fields of 
> the same record.

OK, thanks.


This is a thing in OCaml, I really hate. :(

The only thing I really hate in OCaml....
  ...and I again and again forget this thing... :(
     ...maybe I use Arrays too seldom to remember it...

> 
> You probably want:
> 
> Array.init (width * height) (fun i ->
{red=0;green=0;blue=0})

OK, thanks...

... and in that case I also can use the correct values while
doing it,
so I can throw out the later loop completely.


Thanks,
   Oliver



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