Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask
 
PerlMonks  

comment on

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

Okay. I see what you are saying now. The slice across the return from sort generates a lazy list.

So the code:

my @data = getdata( 100000 ); my @topN = ( sort( @data ) )[ 1 .. 10 ]; undef( @data ); for my $top ( @topN ) { ## << COrrect per 427878 ## do something with $top }

Passes the whole list of data to sort, (which takes a copy of it in case we modify or discard it) and returns an iterator which gets bound to @top, so that each time we access the next element of @top in the for loop, the iterator is called via the magic of tieing, and the copy of the 100,000 elements that we passed to sort gets scanned to produce the next of our 5 return values.

Lazy huh?!


Examine what is said, not who speaks.
Silence betokens consent.
Love the truth but pardon error.

In reply to Re^6: Better mousetrap (getting top N values from list X) by BrowserUk
in thread Better mousetrap (getting top N values from list X) by Limbic~Region

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



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others drinking their drinks and smoking their pipes about the Monastery: (2)
As of 2022-09-28 12:24 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    I prefer my indexes to start at:




    Results (124 votes). Check out past polls.

    Notices?