Beefy Boxes and Bandwidth Generously Provided by pair Networks
We don't bite newbies here... much
 
PerlMonks  

Comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Hi,

I recently made the rookie mistake of authoring a perl script with a sample data input file that was not realistic in size. So now I am running the script with much larger data input files and it is painfully slow. Here is the root cause of the problem:-

1) A data input file is parsed, and each line of the file is added to an array like so:-

push (@StatsArray, {RegionNum=>$RegionNum, AR=>$AR[$RegionNum], BCR=>$BCR[$RegionNum]});
I like the data structure above because it is easy to understand and I can add new elements to the array as the script becomes more sophisticated. I included only 3 of 15 variables, and I expect the number of variables to increase a little more.

2) Once the array is fully populated (millions of entries) and I need to pluck data from it, I need to do two things: a) *always* numerically sort by RegionNum first and then b) numerically sort some other key. Here is an example:-
foreach $RegionCoords (@AllRegionCoords) { $RegionNum++; foreach (sort {$$a{RegionNum} <=> $$b{RegionNum} or $$a{AR} <=> $ +$b{AR}} @StatsArray) { $RegionKey = $$_{RegionNum}; $ARKey = $$_{AR}; if ($RegionKey == $RegionNum) { # do stuff with sorted AR data in region n } } }
Again, easy to follow. The problem is there are many different region numbers and I am not breaking down the data into smaller chunks. For example, although there may be 1 million entries in @StatsArray, all of the entries are made up of, say, 10 region numbers with 100,000 entries in each one. So instead of sorting only 100,000 entries at a time, I am always sorting 1 million entries at a time. A lot of separate sorts are issued, hence the runtime problem.

I have two questions:-

1) How can I reformat the StatsArray to be dependent upon region numbers and make sorting faster? 10 StatsArrays instead of 1 would be fine.

2) If a new data structure is proposed, how would I numerically sort something like the AR key? This is really what I am struggling with the most: ways to sort only 1 of n keys in an array when its data structure gets more complicated.

I do not use arrays like this very often, so any suggestions would be much appreciated.

Thanks!

-fiddler42

In reply to How to improve this data structure? by fiddler42

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and all is quiet...

    How do I use this? | Other CB clients
    Other Users?
    Others chilling in the Monastery: (4)
    As of 2018-07-20 01:37 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?
      It has been suggested to rename Perl 6 in order to boost its marketing potential. Which name would you prefer?















      Results (422 votes). Check out past polls.

      Notices?