PHP group certain results from foreach on array into another array

Question

I have an array that looks something like this:

$array =  array( [0] => FILE-F01-E1-S01.pdf 
                 [1] => FILE-F01-E1-S02.pdf 
                 [2] => FILE-F01-E1-S03.pdf 
                 [3] => FILE-F01-E1-S04.pdf 
                 [4] => FILE-F01-E1-S05.pdf 
                 [5] => FILE-F02-E1-S01.pdf 
                 [6] => FILE-F02-E1-S02.pdf 
                 [7] => FILE-F02-E1-S03.pdf );

Basically, I need to look at the first file and then get all the other files that have the same beginning ('FILE-F01-E1', for example) and put them into an array. I don't need to do anything with the other ones at this point.

I've been trying to use a foreach loop finding the previous value to do this, but am not having any luck.

Like this:

$previousFile = null;

foreach($array as $file)
{

    if(substr_replace($previousFile, "", -8) == substr_replace($file, "", -8)) 
    {
        $secondArray[] = $file;
     }

    $previousFile = $file;
}

So then $secondArray would look like this:

    Array ( [0] => FILE-F01-E1-S01.pdf [1] => FILE-F01-E1-S02.pdf 
            [2] => FILE-F01-E1-S03.pdf [3] => FILE-F01-E1-S04.pdf 
            [4] => FILE-F01-E1-S05.pdf)

As my result.

Thank you!

Sample code always helps to see where you are so far. Would it be possible to use a simple foreach() and if(), with a regular expression condition? — HoldOffHunger
– HoldOffHunger, Commented Sep 27, 2018 at 18:40
First you need to define your pattern. Is it always going to be FILE-F[NUMBER]-*.pdf ? What is your use case for the array? Do you just want to get let's say F01 files array or you want to parse them all at once into their separate arrays? Please provide us with more context. — Jan Richter
– Jan Richter, Commented Sep 27, 2018 at 18:43
@falnyr The files will vary in how they are named. I can't do a strpos() on them because it will differ. I can, however always remove the last 8 characters to match them. And, yes, I do just want an array of F01 files. That's all I need to do at this point. I hope that clears things up a bit. — matty_eng
– matty_eng, Commented Sep 27, 2018 at 18:51
@matty_eng Are you sure about the last 8 characters? What you are showing here seems to be a list of episodes for a TV show. What if the name would be E01-S1 can that happen? — Jan Richter
– Jan Richter, Commented Sep 27, 2018 at 18:55
Why are you reassigning $previousFile every time through the loop? You said you just want to use the first file to get the pattern. — Barmar
– Barmar, Commented Sep 27, 2018 at 19:09

Jeto · Accepted Answer · 2018-09-27 18:43:37Z

1

You can use array_filter combined with strpos:

$result = array_filter($array, function($filename) { 
  return strpos($filename, 'FILE-F01-E1') === 0; 
});

answered Sep 27, 2018 at 18:43

Jeto

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inquam · Accepted Answer · 2018-09-27 19:06:43Z

0

Are you sure this will be the naming format? That is crucial information to have to construct a regexp or something to check for being a substring of the following strings.

If we can assume this and that the "base" name is always at index 0 then you could do something like.

<?php
    $myArr =  [ 
                'FILE-F01-E1-S01.pdf', 
                'FILE-F01-E1-S02.pdf', 
                'FILE-F01-E1-S03.pdf', 
                'FILE-F01-E1-S04.pdf', 
                'FILE-F01-E1-S05.pdf', 
                'FILE-F02-E1-S01.pdf', 
                'FILE-F02-E1-S02.pdf', 
                'FILE-F02-E1-S03.pdf'
              ];

    $baseName        = '';
    $allSimilarNames = [];

    foreach($myArr as $index => &$name) {
      if($index == 0) {
          $baseName = substr($name, 0, strrpos($name, '-'));
          $allSimilarNames[] = $name;
      }
      else {
          if(strpos($name, $baseName) === 0) {
              $allSimilarNames[] = $name;
          }
      }
    }

    var_dump($allSimilarNames);

This will

Check at index one to get the base name to compare against
Loop all items in the array and match all items, no matter where in the array they are, that are similar according to your naming convention

So if you next time have an array that is

$myArr =  [ 
                    'FILE-F02-E1-S01.pdf',
                    'FILE-F01-E1-S01.pdf', 
                    'FILE-F01-E1-S02.pdf', 
                    'FILE-F01-E1-S03.pdf', 
                    'FILE-F01-E1-S04.pdf', 
                    'FILE-F01-E1-S05.pdf', 
                    'FILE-F02-E1-S02.pdf', 
                    'FILE-F02-E1-S03.pdf'
                  ];

this will return all the items that match FILE-F02-E1*.

You could also make a small function of it for easier use and not have to rely on the element at index 0 having to be the "base" name.

<?php
function findMatches($baseName, &$names) {
    $matches = [];
    $baseName = substr($baseName, 0, strrpos($baseName, '-'));
    foreach($names as &$name) {
        if(strpos($name, $baseName) === 0) {
          $matches[] = $name;
        }
    }

    return $matches;
}

$myArr =  [ 
            'FILE-F01-E1-S01.pdf', 
            'FILE-F01-E1-S02.pdf', 
            'FILE-F01-E1-S03.pdf', 
            'FILE-F01-E1-S04.pdf', 
            'FILE-F01-E1-S05.pdf', 
            'FILE-F02-E1-S01.pdf', 
            'FILE-F02-E1-S02.pdf', 
            'FILE-F02-E1-S03.pdf'
          ];

$allSimilarNames = findMatches('FILE-F01-E1-S01.pdf', $myArr);

var_dump($allSimilarNames);

edited Sep 27, 2018 at 19:06

answered Sep 27, 2018 at 18:49

inquam

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3 Comments

Barmar Over a year ago

Instead of testing $index == 0 every time through the loop, why not just initialize $baseName using $myArr[0]?

matty_eng Over a year ago

Thank you! I think this is exactly what I needed.

inquam Over a year ago

@Barmar: I initially had the check since I was unsure that the item at index 0 should be part of the result. So I first never added that to the array. Then when I changed it I didn't refactor the code flow. That is why I added the example with making it a function instead since that is a "better" solution. The initial one with the reach was just a quick and dirty solution.

Rook · Accepted Answer · 2018-09-27 18:53:14Z

0

Run a simple foreach with strpos() which looks for an occurrence of a string within a string.

 $results = array();

 foreach($array as $item){
      if (strpos($item, 'FILE-F01-E1') === 0) {
           array_push($results, $item);
      }
 }

edited Sep 27, 2018 at 18:53

answered Sep 27, 2018 at 18:43

Rook

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7 Comments

Jeto Over a year ago

I believe your strpos test is wrong. First position will return 0 which doesn't evaluate to true. Any other position will evaluate to true (after your edit, with === the condition will never be met now :) )

Rook Over a year ago

Thanks. I believe that I have fixed it!

Jeto Over a year ago

Almost: I believe you meant === 0. You want to add the items which do have that string at their first position.

Rook Over a year ago

Ah yes. To be honest, this is not the best use of strpos(). I appreciate the corrections! I actually was unaware of the array_filter() function! Very handy.

Rook Over a year ago

@inquam Thanks for the feedback. However I am only interested in the condition being met if the position of the desired string is at place 0. I don't want to condition to be met if it is indeed false.

|

The fourth bird · Accepted Answer · 2018-09-27 20:11:04Z

You could get the first item from the array and use explode and implode to get the part from the filename without the last hyphen and the content after that.

Then use array_filter and use substr using 0 as the start position and the length of the $fileBeginning as the length to check if the string starts with FILE-F01-E1:

$array = [
    'FILE-F01-E1-S01.pdf',
    'FILE-F01-E1-S02.pdf',
    'FILE-F01-E1-S03.pdf',
    'FILE-F01-E1-S04.pdf',
    'FILE-F01-E1-S05.pdf',
    'FILE-F02-E1-S01.pdf',
    'FILE-F02-E1-S02.pdf',
    'FILE-F02-E1-S03.pdf',
    "TESTFILE-F01-E1-S03.pdf"
];
$parts = explode('-', $array[0]);
array_pop($parts);
$fileBeginning =  implode('-', $parts);
$secondArray = array_filter($array, function ($x) use ($fileBeginning) {
    return substr($x, 0, strlen($fileBeginning)) === $fileBeginning;
});
print_r($secondArray);

Result

Array
(
    [0] => FILE-F01-E1-S01.pdf
    [1] => FILE-F01-E1-S02.pdf
    [2] => FILE-F01-E1-S03.pdf
    [3] => FILE-F01-E1-S04.pdf
    [4] => FILE-F01-E1-S05.pdf
)

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