Eliminate Partial Strings from Array of Strings PHP

Question

I can do this, I'm just wondering if there is a more elegant solution than the 47 hacked lines of code I came up with...

Essentially I have an array (the value is the occurrences of said string);

[Bob] => 2
[Theresa] => 3
[The farm house] => 2
[Bob at the farm house] => 1

I'd like to iterate through the array and eliminate any entries that are sub-strings of others so that the end result would be;

[Theresa] => 3
[Bob at the farm house] => 1

Initially I was looping like (calling this array $baseTags):

foreach($baseTags as $key=>$count){
   foreach($baseTags as $k=>$c){
      if(stripos($k,$key)){
            unset($baseTags[$key]);
      }
   }
}

I'm assuming I'm looping through each key in the array and if there is the occurrence of that key inside another key to unset it... doesn't seem to be working for me though. Am I missing something obvious?

Thank you in advance.

-H

Marc B · Accepted Answer · 2012-11-14 16:05:18Z

1

You're mis-using strpos/stripos. They can return a perfectly valid 0 if the string you're searching for happens to be at the START of the 'haystack' string, e.g. your Bob value. You need to explicitly test for this with

if (stripos($k, $key) !== FALSE) {
   unset(...);
}

if strpos/stripos don't find the needle, they return a boolean false, which under PHP's normal weak comparison rules is equal/equivalent to 0. Using the strict comparison operators (===, !==), which compare type AND value, you'll get the proper results.

answered Nov 14, 2012 at 16:05

Marc B

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2 Comments

Howard Zoopaloopa Over a year ago

=== will be the death of me. Many thanks. I'll check you correct once SO lets me.

hakre Over a year ago

That if has also an additional problem according to what you want to achieve. See stackoverflow.com/a/13383210/367456

Adam · Accepted Answer · 2012-11-14 16:24:01Z

1

Don't forget as-well as needing !== false, you need $k != $key so your strings don't match themselves.

edited Nov 14, 2012 at 16:24

answered Nov 14, 2012 at 16:14

Adam

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1 Comment

Howard Zoopaloopa Over a year ago

funny, I literally just added that :)

hakre · Accepted Answer · 2012-11-14 16:42:26Z

You have two problems inside your code-example:

You combine each key with each key, so not only others, but also itself. You would remove all entries so because "Bob" is a substring of "Bob", too.
stripos returns false if not found which can be confused with 0 that stands for found at position 0, which is also equal but not identical to false.

You need to add an additional check to not remove the same key and then fix the check for the "not found" case (Demo):

$baseTags = array(
    'Bob' => 2,
    'Theresa' => 3,
    'The farm house' => 2,
    'Bob at the farm house' => 1,
);

foreach ($baseTags as $key => $count)
{
   foreach ($baseTags as $k => $c)
   {
      if ($k === $key)
      {
          continue;
      }

      if (false !== stripos($k, $key))
      {
            unset($baseTags[$key]);
      }
   }
}

print_r($baseTags);

Output:

Array
(
    [Theresa] => 3
    [Bob at the farm house] => 1
)

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