Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl: the Markov chain saw

comment on

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

Given a string of bytes, I want to split the string into chunks of the same byte value, as efficiently as possible. Ie. Given 'aaabcccdeeefffggg', get 'aaa','b','ccc','d','eee','fff','ggg'. The string of bytes can contain *any* values 0 .. 255.

I thought this would be easy, but has actually proved to be quite hard. The fastest, and in fact only way I've found is shown below. Test b checks the cost of the /m modifier, but is just a placeholder for something better...

$s = join'', map{ chr( 65+rand(26) ) x rand( 100 ) } 1 .. 1000;; cmpthese -1,{ a=>q[ 1 while $s =~ m[((?=(.))\2+)]g; ], b=>q[ 1 while $s =~ m[((?=(.))\2+)]mg; ] };; Rate a b a 203/s -- -1% b 205/s 1% --

Anyone see a better, ie. more efficient way?

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority". The enemy of (IT) success is complexity.
In the absence of evidence, opinion is indistinguishable from prejudice.

In reply to Faster regex to split a string into runs of similar characters? by BrowserUk

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 How to display code and escape characters are good places to start.
Log In?

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

How do I use this? | Other CB clients
Other Users?
Others lurking in the Monastery: (4)
As of 2023-06-08 21:43 GMT
Find Nodes?
    Voting Booth?
    How often do you go to conferences?

    Results (35 votes). Check out past polls.