Search Pattern Frequency

Question

Preferably PHP solutions -- but any ideas would be great.

Give a text blob

'This is a super string of some content whree I want to find red sweaters and purple elephants. The purple elephants will count twice. and the red sweaters will count 3 times since red sweaters occurs three times'

and a phrase list

'red sweaters, purple elephants'

want to search the text blob and return count of occurances

therefore

red sweaters = 3 and purple elephants = 2

http://cz2.php.net/manual/en/function.preg-match-all.php – Krab Dec 06 '11 at 16:59 — Krab, Dec 06 '11 at 16:59
Is this Homework? If yes, tag appropriately! :) – mac Dec 06 '11 at 20:14 — mac, Dec 06 '11 at 20:14

score 4 · Accepted Answer · answered Dec 06 '11 at 16:58

4

http://www.php.net/manual/en/function.substr-count.php

$string = 'This is a super string of some content whree I want to find red sweaters and purple elephants. The purple elephants will count twice. and the red sweaters will count 3 times since red sweaters occurs three times';

$keys = 'red sweaters, purple elephants';

$pkeys = explode(', ', $keys);
foreach($pkeys as $key)
{
    printf("%s occourrences: %d\n", $key, substr_count($string, $key));
}

answered Dec 06 '11 at 16:58

Strae

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DaNieL - thanks.. I think I was over-engineering it!! Do you think that there is a benegit to substr_count over preg_match ? – cgmckeever Dec 06 '11 at 19:22
substr_count works differents from preg_match_all function - as noticed by amosrivera, substr_count() will hit, in you case, even brownred sweaters becose contain the string you use as needle. With preg_match_all you can define more complex (and precise) rules, for example you can do a case-insensitive search without modify the original string (as suggested Nick).. all depends on what do you need to do – Strae Dec 06 '11 at 20:59

score 2 · Answer 2 · answered Dec 06 '11 at 17:05

2

You can use substr_count which will search for strings inside a text. Just note that in your example if the text was "brownred sweaters" that will count +1 for "red sweaters".

You can also use regular expressions. Something like preg_match("/$string/",$text);. This would return the times the string was found.

Also if you want to search for several strings delimited by a comma (like your example) you first need to split the string. You can use explode for this. $strings = explode(",",$search);

answered Dec 06 '11 at 17:05

amosrivera

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+1 for a more detailed answer than mine; even if regexp looks a bit overkill in this situation for me, your answer offer more solutions ;) – Strae Dec 06 '11 at 17:13
@DaNieL funny because i had upvoted your answer for being more straight forward ;) – amosrivera Dec 06 '11 at 17:21

score 1 · Answer 3 · answered Dec 06 '11 at 17:03

Something like this should work:

<?php
  $string = strtolower('This is a super string of some content whree I want to find red sweaters and purple elephants. The purple elephants will count twice. and the red sweaters will count 3 times since red sweaters occurs three times');

  $allprases = 'red sweaters, purple elephants'

  $phrasearray = explode(',',$allphrases);

  foreach ($phrasearray as $k => $phrase) {
    $phrase = strtolower(trim($phrase));
    echo 'String '.$phrase.' found '.substr_count($string,$phrase).' times.<br />';
  }
?>

Do note that substr_count is case sensitive (which is why I'm strtolower()ing everything in the above code). This can be removed easily enough so that the code above is case sensitive too.

Search Pattern Frequency

3 Answers3