Explode a Paragraph into Sentences in PHP

Explode a paragraph into sentences in PHP

You can do:

preg_split('/\.|\?|!/',$mystring);

or (simpler):

preg_split('/[.?!]/',$mystring);

Split a text into sentences

Since you want to "split" sentences why are you trying to match them ?

For this case let's use preg_split().

Code:

$str = 'Fry me a Beaver. Fry me a Beaver! Fry me a Beaver? Fry me Beaver no. 4?! Fry me many Beavers... End';
$sentences = preg_split('/(?<=[.?!])\s+(?=[a-z])/i', $str);
print_r($sentences);

Output:

Array
(
    [0] => Fry me a Beaver.
    [1] => Fry me a Beaver!
    [2] => Fry me a Beaver?
    [3] => Fry me Beaver no. 4?!
    [4] => Fry me many Beavers...
    [5] => End
)

Explanation:

Well to put it simply we are spliting by grouped space(s) \s+ and doing two things:

1. (?<=[.?!]) Positive look behind assertion, basically we search if there is a point or question mark or exclamation mark behind the space.

2. (?=[a-z]) Positive look ahead assertion, searching if there is a letter after the space, this is kind of a workaround for the no. 4 problem.

PHP trying to split paragraph into sentences. Keep punctuation

Here's what I have:

<?php

/**
 * @param string $str                          String to split
 * @param string $end_of_sentence_characters   Characters which represent the end of the sentence. Should be a string with no spaces (".,!?")
 *
 * @return array
 */
function split_sentences($str, $end_of_sentence_characters) {
    $inside_quotes = false;
    $buffer = "";
    $result = array();
    for ($i = 0; $i < strlen($str); $i++) {
        $buffer .= $str[$i];
        if ($str[$i] === '"') {
            $inside_quotes = !$inside_quotes;
        }
        if (!$inside_quotes) {
            if (preg_match("/[$end_of_sentence_characters]/", $str[$i])) {
                $result[] = $buffer;
                $buffer = "";
            }
        }
    }
    return $result;
}

$str = <<<STR
One morning, when Gregor Samsa woke from troubled dreams, he found himself transformed in his bed into a horrible vermin. "What has happened!?" he asked himself. "I... don't know." said Samsa, "Maybe this is a bad dream." He lay on his armour-like back, and if he lifted his head a little he could see his brown belly, slightly domed and divided by arches into stiff sections.
STR;

var_dump(split_sentences($str, "."));

Splitting paragraph into sentences keeping the punctuations - not a dup

Your requirement doesn't need PREG_SPLIT_DELIM_CAPTURE. It's helpful when you need them to be returned as individual matches. In this case you need \K:

<?php

var_dump(preg_split('~("[^"]*")|[!?.।]+\K\s*|\R+~u', <<<STR
hello! how are you? how is life
live life, live free. "isnt it?"
STR
, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY));

Output:

array(5) {
  [0]=>
  string(6) "hello!"
  [1]=>
  string(12) "how are you?"
  [2]=>
  string(11) "how is life"
  [3]=>
  string(21) "live life, live free."
  [4]=>
  string(10) ""isnt it?""
}

Get first 2 sentences in php

You could use preg_split with a regex for the endings that you want with the PREG_SPLIT_DELIM_CAPTURE option, this will maintain the punctuation used.

function createCustomDescription($string) {
    $split = preg_split('/(\.|\!|\?)/', $string, 3, PREG_SPLIT_DELIM_CAPTURE);
    $custom_desc = implode('', array_slice($split, 0, 4));

    return htmlspecialchars($custom_desc);
}

Split string into sentences using regex

As it should be expected, any sort of natural language processing is not a trivial task. The reason for it is that they are evolutionary systems. There is no single person who sat down and thought about which are good ideas and which - not. Every rule has 20-40% exceptions. With that said the complexity of a single regex that can do your bidding would be off the charts. Still, the following solution relies mainly on regexes.

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• The idea is to gradually go over the text.
• At any given time, the current chunk of the text will be contained in two different parts. One, which is the candidate for a substring before a sentence boundary and another - after.
• The first 10 regex pairs detect positions which look like sentence boundaries, but actually aren't. In that case, before and after are advanced without registering a new sentence.
• If none of these pairs matches, matching will be attempted with the last 3 pairs, possibly detecting a boundary.

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As for where did these regexes come from? - I translated this Ruby library, which is generated based on this paper. If you truly want to understand them, there is no alternative but to read the paper.

As far as accuracy goes - I encourage you to test it with different texts. After some experimentation, I was very pleasantly surprised.

In terms of performance - the regexes should be highly performant as all of them have either a \A or \Z anchor, there are almost no repetition quantifiers, and in the places there are - there can't be any backtracking. Still, regexes are regexes. You will have to do some benchmarking if you plan to use this is tight loops on huge chunks of text.

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Mandatory disclaimer: excuse my rusty php skills. The following code might not be the most idiomatic php ever, it should still be clear enough to get the point across.

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function sentence_split($text) {
    $before_regexes = array('/(?:(?:[\'\"„][\.!?…][\'\"”]\s)|(?:[^\.]\s[A-Z]\.\s)|(?:\b(?:St|Gen|Hon|Prof|Dr|Mr|Ms|Mrs|[JS]r|Col|Maj|Brig|Sgt|Capt|Cmnd|Sen|Rev|Rep|Revd)\.\s)|(?:\b(?:St|Gen|Hon|Prof|Dr|Mr|Ms|Mrs|[JS]r|Col|Maj|Brig|Sgt|Capt|Cmnd|Sen|Rev|Rep|Revd)\.\s[A-Z]\.\s)|(?:\bApr\.\s)|(?:\bAug\.\s)|(?:\bBros\.\s)|(?:\bCo\.\s)|(?:\bCorp\.\s)|(?:\bDec\.\s)|(?:\bDist\.\s)|(?:\bFeb\.\s)|(?:\bInc\.\s)|(?:\bJan\.\s)|(?:\bJul\.\s)|(?:\bJun\.\s)|(?:\bMar\.\s)|(?:\bNov\.\s)|(?:\bOct\.\s)|(?:\bPh\.?D\.\s)|(?:\bSept?\.\s)|(?:\b\p{Lu}\.\p{Lu}\.\s)|(?:\b\p{Lu}\.\s\p{Lu}\.\s)|(?:\bcf\.\s)|(?:\be\.g\.\s)|(?:\besp\.\s)|(?:\bet\b\s\bal\.\s)|(?:\bvs\.\s)|(?:\p{Ps}[!?]+\p{Pe} ))\Z/su',
        '/(?:(?:[\.\s]\p{L}{1,2}\.\s))\Z/su',
        '/(?:(?:[\[\(]*\.\.\.[\]\)]* ))\Z/su',
        '/(?:(?:\b(?:pp|[Vv]iz|i\.?\s*e|[Vvol]|[Rr]col|maj|Lt|[Ff]ig|[Ff]igs|[Vv]iz|[Vv]ols|[Aa]pprox|[Ii]ncl|Pres|[Dd]ept|min|max|[Gg]ovt|lb|ft|c\.?\s*f|vs)\.\s))\Z/su',
        '/(?:(?:\b[Ee]tc\.\s))\Z/su',
        '/(?:(?:[\.!?…]+\p{Pe} )|(?:[\[\(]*…[\]\)]* ))\Z/su',
        '/(?:(?:\b\p{L}\.))\Z/su',
        '/(?:(?:\b\p{L}\.\s))\Z/su',
        '/(?:(?:\b[Ff]igs?\.\s)|(?:\b[nN]o\.\s))\Z/su',
        '/(?:(?:[\"”\']\s*))\Z/su',
        '/(?:(?:[\.!?…][\x{00BB}\x{2019}\x{201D}\x{203A}\"\'\p{Pe}\x{0002}]*\s)|(?:\r?\n))\Z/su',
        '/(?:(?:[\.!?…][\'\"\x{00BB}\x{2019}\x{201D}\x{203A}\p{Pe}\x{0002}]*))\Z/su',
        '/(?:(?:\s\p{L}[\.!?…]\s))\Z/su');
    $after_regexes = array('/\A(?:)/su',
        '/\A(?:[\p{N}\p{Ll}])/su',
        '/\A(?:[^\p{Lu}])/su',
        '/\A(?:[^\p{Lu}]|I)/su',
        '/\A(?:[^p{Lu}])/su',
        '/\A(?:\p{Ll})/su',
        '/\A(?:\p{L}\.)/su',
        '/\A(?:\p{L}\.\s)/su',
        '/\A(?:\p{N})/su',
        '/\A(?:\s*\p{Ll})/su',
        '/\A(?:)/su',
        '/\A(?:\p{Lu}[^\p{Lu}])/su',
        '/\A(?:\p{Lu}\p{Ll})/su');
    $is_sentence_boundary = array(false, false, false, false, false, false, false, false, false, false, true, true, true);
    $count = 13;

    $sentences = array();
    $sentence = '';
    $before = '';
    $after = substr($text, 0, 10);
    $text = substr($text, 10);

    while($text != '') {
        for($i = 0; $i < $count; $i++) {
            if(preg_match($before_regexes[$i], $before) && preg_match($after_regexes[$i], $after)) {
                if($is_sentence_boundary[$i]) {
                    array_push($sentences, $sentence);
                    $sentence = '';
                }
                break;
            }
        }

        $first_from_text = $text[0];
        $text = substr($text, 1);
        $first_from_after = $after[0];
        $after = substr($after, 1);
        $before .= $first_from_after;
        $sentence .= $first_from_after;
        $after .= $first_from_text;
    }

    if($sentence != '' && $after != '') {
        array_push($sentences, $sentence.$after);
    }

    return $sentences;
}

$text = "Mr. Entertainment media properties. Fairy Tail 3.5 and Tokyo Ghoul.";
print_r(sentence_split($text));

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