PHP Searching Array for Start and End point of values

Question

I have an array as follows:

Array (
[0] => Array (
  ...
)
[41] => Array (
  [name] => London 
  [company] => nhyt6t
  [top25_1] => 8.75912088
)
[42] => Array (
  [name] => Manchester
  [company] => gtr4rf
  [top25_1] => 6.56758398
)
[43] => Array (
  [name] => Leeds
  [company] => de3wsd6
  [top25_1] => 7.58675398
)
[44] => Array (
  [name] => Liverpool
  [company] => fe4rf56
  [top25_2] => 4.5697965
)
)

Is it possible (within PHP) to search the array and bring back the Array Index for the Start and End of top25_1 (Note: they are always grouped in a sequence) - so in this instance:

$start = 41;
$end = 43;

The position of top25_1 varies each time the array is generated, hence the need to search.

Any advice, feedback and assistance welcomed.

Check to see if key exists, see php.net/manual/en/function.array-key-exists.php — ggdx
– ggdx, Commented Jul 4, 2014 at 12:25
Will they always be grouped in a sequence, or could a different key like top25_99 interrupt the sequence? — Michael Berkowski
– Michael Berkowski, Commented Jul 4, 2014 at 12:27
@dwhite.me - looking at that it merely returns True is the key exists, I need the Index Value returned. — Homer_J
– Homer_J, Commented Jul 4, 2014 at 12:30

Alma Do · Accepted Answer · 2014-07-04 13:03:10Z

1

You may do it with:

$result = array_reduce(array_keys($array), function($c, $x) use ($array)
{
   if(!isset($c[$key = end(array_keys($array[$x]))]))
   {
      $c[$key] = array('start'=>$x, 'end'=>$x);
   }
   else
   {
      $c[$key]['end'] = $x;
   };
   return $c;
}, array());

So, result of statement above would be array, which has your top_XX as keys and ['start'=>Y, 'end'=>Z] as values, where Y and Z are corresponding groups starts and ends. For example, if input array is:

$array = array(
    41 => Array (
      'name' => 'London ',
      'company' => 'nhyt6t',
      'top25_1' => 8.75912088
    ),
    42 => Array (
      'name' => 'Manchester',
      'company' => 'gtr4rf',
      'top25_1' => 6.56758398
    ),
    43 => Array (
      'name' => 'Leeds',
      'company' => 'de3wsd6',
      'top25_1' => 7.58675398
    ),
    44 => Array (
      'name' => '--- ',
      'company' => 'nhyt6t',
      'top25_2' => 1
    ),
    45 => Array (
      'name' => '---',
      'company' => 'gtr4rf',
      'top25_2' => 1
    ),
    46 => Array (
      'name' => '??',
      'company' => 'de3wsd6',
      'top25_3' => 7.58675398
    )
);

Then result would be:

array(3) {
  ["top25_1"]=>
  array(2) {
    ["start"]=>
    int(41)
    ["end"]=>
    int(43)
  }
  ["top25_2"]=>
  array(2) {
    ["start"]=>
    int(44)
    ["end"]=>
    int(45)
  }
  ["top25_3"]=>
  array(2) {
    ["start"]=>
    int(46)
    ["end"]=>
    int(46)
  }
}

That means you can easily get desired key start and end with $result[$key] (so, $result['top25_1'] for your question)

Please, note that statement above relies on fact, that your elements are grouped - thus, is they're not - then result may be unexpected.

edited Jul 4, 2014 at 13:03

answered Jul 4, 2014 at 12:47

Alma Do

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2 Comments

Homer_J Over a year ago

That looks like it is exactly what I am after, however, your code stops mine from working and I cannot see why!

Alma Do Over a year ago

You mean it doesn't work? It may be short arrays syntax (so. [..]) - you may replace it to array(..) if you're on PHP 5.3

Katch · Accepted Answer · 2014-07-04 12:46:24Z

1

Loop through your array and check if the array contains your key, like so:

$start = null;
$end = 0;
foreach($arrays as $k => $arr) {
  if (array_key_exists('top25_1', $arr)) {
    if ($start === null) { // only update with the first key
       $start = $k; // 41
    }

    if ($k > $end) { // if the array key is bigger than the last end, update.
       $k = $end; // 43
    }
  }
}

edited Jul 4, 2014 at 12:46

answered Jul 4, 2014 at 12:30

Katch

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4 Comments

Michael Berkowski Over a year ago

But the // some code here is what is important to get the first and last. That's what the OP needs.

Homer_J Over a year ago

@Airoude - this is fine but it's pulling out the Array Index Value of the first and last time that top25_1 appears.

Katch Over a year ago

So you want the value of top25_1?

Homer_J Over a year ago

@Airoude - nope. As stated in the question. I need the Array Index Value of top25_1 when it starts (i.e. first appears in the Array) and where it ends (i.e. the last time it appears).

Zemistr · Accepted Answer · 2014-07-04 13:34:52Z

1

$start = null;
$end = null;

while(list($index, $item) = each($array)) {
    if(isset($item['top25_1'])) {
        if($start === null) {
            $start = $index;
        }

        $end = $index;
    }
}

Description:

Array (
    [0] => Array (
      ... // do nothing
    )
    [41] => Array (
        [name] => London 
      [company] => nhyt6t
      [top25_1] => 8.75912088 // set start and end
    )
    [42] => Array (
        [name] => Manchester
      [company] => gtr4rf
      [top25_1] => 6.56758398 // update end
    )
    [43] => Array (
        [name] => Leeds
      [company] => de3wsd6
      [top25_1] => 7.58675398 // update end
    )
    [44] => Array (
        [name] => Liverpool
      [company] => fe4rf56
      [top25_2] => 4.5697965 // do nothing
    )
)

edited Jul 4, 2014 at 13:34

answered Jul 4, 2014 at 12:52

Zemistr

1,0497 silver badges10 bronze badges

4 Comments

DavidG Over a year ago

Care to explain this?

Zemistr Over a year ago

Why? :D After all, it's simple. ;)

DavidG Over a year ago

StackOverflow exists to help people improve, giving someone code without explanation might help this person but not necessarily the next person to come along and read it. This answer was flagged as low quality because of this.

DavidG Over a year ago

Much better, take a look at the answer from @AlmaDo on how you could improve it even more.

javier_domenech · Accepted Answer · 2014-07-04 12:57:56Z

0

$init = -1;
$end = -1;
for($i=0;$i<count($array);$i++) {
  if ($init == -1 and array_key_exists('top25_1', $array[$i])) {
    $init=$i;

  }
  if($init>=0 and !array_key_exists('top25_1', $array[$i]))
  {
     $end=$i - 1;
     break;
  }

}
if($init>=0 and $end==-1)
   $end = count($array) -1;

edited Jul 4, 2014 at 12:57

answered Jul 4, 2014 at 12:35

javier_domenech

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4 Comments

EaterOfCode Over a year ago

and what if the first or last top25_1 is at 0?

Homer_J Over a year ago

@vivoconunxino - Thanks for this - however, for some reason your code is causing mine to stop working.

Homer_J Over a year ago

FYI - PHP Syntax Check: Parse error: syntax error, unexpected ')', expecting ';' in your code on line 3 for($i=0;$i<count($array),$i++) {

javier_domenech Over a year ago

well... easy to fix, here you go

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