How can multiple identical values be printed from an array in PHP? - php

Question

I'm trying to create a basic concordance script that will print the ten words before and after the value found inside an array. I did this by splitting the text into an array, identifying the position of the value, and then printing -10 and +10 with the searched value in the middle. However, this only presents the first such occurrence. I know I can find the others by using array_keys (found in positions 52, 78, 80), but I'm not quite sure how to cycle through the matches, since array_keys also results in an array. Thus, using $matches (with array_keys) in place of $location below doesn't work, since you cannot use the same operands on an array as an integer. Any suggestions? Thank you!!
<?php
$text = <<<EOD
The spread of a deadly new virus is accelerating, Chinese President Xi Jinping warned, after holding a special government meeting on the Lunar New Year public holiday.
The country is facing a "grave situation" Mr Xi told senior officials.
The coronavirus has killed at least 42 people and infected some 1,400 since its discovery in the city of Wuhan.
Meanwhile, UK-based researchers have warned of a real possibility that China will not be able to contain the virus.
Travel restrictions have come in place in several affected cities. From Sunday, private vehicles will be banned from central districts of Wuhan, the source of the outbreak.
EOD;
$new = explode(" ", $text);
$location = array_search("in", $new, FALSE);
$concordance = 10;
$top_range = $location + $concordance;
$bottom_range = $location - $concordance;
while($bottom_range <= $top_range) {
echo $new[$bottom_range] . " ";
$bottom_range++;
}
?>

Answer 1

You can just iterate over the values returned by array_keys, using array_slice to extract the $concordance words either side of the location and implode to put the sentence back together again:
$words = explode(' ', $text);
$concordance = 10;
$results = array();
foreach (array_keys($words, 'in') as $idx) {
$results[] = implode(' ', array_slice($words, max($idx - $concordance, 0), $concordance * 2 + 1));
}
print_r($results);
Output:
Array
(
[0] => least 42 people and infected some 1,400 since its discovery in the city of Wuhan.
Meanwhile, UK-based researchers have warned of a
[1] => not be able to contain the virus.
Travel restrictions have come in place in several affected cities. From Sunday, private vehicles will
[2] => able to contain the virus.
Travel restrictions have come in place in several affected cities. From Sunday, private vehicles will be banned
)
If you want to avoid generating similar phrases where a word occurs twice within $concordance words (e.g. indexes 1 and 2 in the above array), you can maintain a position for the end of the last match, and skip occurrences that occur in that match:
$words = explode(' ', $text);
$concordance = 10;
$results = array();
$last = 0;
foreach (array_keys($words, 'in') as $idx) {
if ($idx < $last) continue;
$results[] = implode(' ', array_slice($words, max($idx - $concordance, 0), $concordance * 2 + 1));
$last = $idx + $concordance;
}
print_r($results);
Output
Array
(
[0] => least 42 people and infected some 1,400 since its discovery in the city of Wuhan.
Meanwhile, UK-based researchers have warned of a
[1] => not be able to contain the virus.
Travel restrictions have come in place in several affected cities. From Sunday, private vehicles will
)
Demo on 3v4l.org

Answer 2

Try this:
<?php
$text = <<<EOD
The spread of a deadly new virus is accelerating, Chinese President Xi Jinping warned, after holding a special government meeting on the Lunar New Year public holiday.
The country is facing a "grave situation" Mr Xi told senior officials.
The coronavirus has killed at least 42 people and infected some 1,400 since its discovery in the city of Wuhan.
Meanwhile, UK-based researchers have warned of a real possibility that China will not be able to contain the virus.
Travel restrictions have come in place in several affected cities. From Sunday, private vehicles will be banned from central districts of Wuhan, the source of the outbreak.
EOD;
$words = explode(" ", $text);
$concordance = 10; // range -+
$result = []; // result array
$index = 0;
if (count($words) === 0) // be sure there is no empty array
exit;
do {
$location = array_search("in", $words, false);
if (!$location) // break loop if $location not found
break;
$count = count($words);
// check range of array indexes
$minRange = ($location - $concordance > 0) ? ($location-$concordance) : 0; // array can't have index less than 0 (shorthand if)
$maxRange = (($location + $concordance) < ($count - 1)) ? ($location+$concordance) : $count - 1; // array can't have index equal or higher than array count (shorthand if)
for ($range = $minRange; $range < $maxRange; $range++) {
$result[$index][] = $words[$range]; // group words by index
}
unset($words[$location]); // delete element which contain "in"
$words = array_values($words); // reindex array
$index++;
} while ($location); // repeat until $location exist
print_r($result); // <--- here's your results
?>