Compare multiple strings and find similar substrings in php

Question

I have to develop an algorithm that will get multiple strings and find the matched substrings across all those strings. and put percentage to that matched text.

For example

this is first string - 100%

this is second string - 76%

That sounds good but you don't really need to let us know what you're planning to do. You can go ahead and do it and let us know what difficulties you've encountered — apokryfos
– apokryfos, Commented May 12, 2021 at 15:21

Jaquarh · Accepted Answer · 2021-05-13 17:16:23Z

1

Another method would be to work out the differences using php's inbuilt functions then subtract the difference from the count and calculate percentage.

You could put it into one line but for readability, I broke it down into variables.

Note: This requires PHP 7.4^ to execute. Replace the short hand function fn() with function($x) use ($words) { return in_array($x, $words); } if your PHP version does not meet the requirement.

function percentageSubStrings(array $inputs, array $needles): array
{
    $outputs = [];
        
    foreach($inputs as $input)
    {
        $words = explode(' ', $input);
        $difference = array_diff($words, array_filter($needles, fn($x) => in_array($x, $words)));
        $outputs[$input] = ((count($words) - count($difference)) / count($needles)) * 100;
    }
    
    return $outputs;
}

See it working over at 3v4l.org where it is compact.

edited May 13, 2021 at 17:16

answered May 13, 2021 at 17:04

Jaquarh

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Comments

Lajos Arpad · Accepted Answer · 2021-05-12 15:36:05Z

1

A raw PHP solution is

function getStringPercentages(inputs, needles) {
    $outputs = [];
    foreach ($inputs as $input) {
        $count = 0;
        foreach ($needles as $needle) {
            if (strpos($input, $needle) !== false) $count++;
        }
        $outputs[$input] = ($count / count($outputs)) * 100;
    }
}

and then you will need to display the raw percentages nicely.

answered May 12, 2021 at 15:36

Lajos Arpad

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2 Comments

Jaquarh Over a year ago

Rather than nested loops and counters, you could utilise a count() on an array_filter() append: count(array_filter($needles, fn($subStr) => strpos($input, $subStr))) / count($needles) * 100. +1 for concept however.

Lajos Arpad Over a year ago

@Jaquarh yes, that's another possible solution. I've chosen this because it contains an algorithm that the asker might understand. However, standard PHP functions will work just as well.

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