After much searching I haven't been able to find a good explanation on how to use array_multisort() to case insensitively sort a multidimensional array by one field. I find this to be a very helpful feature when dealing with information from database queries so thought I would share.
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3 Answers
I should note this only works in php 5.4+
# Example results from database
$PDOresult = array(
array('name' => 'Alpha', 'price' => '10'),
array('name' => 'beta', 'price' => '12'),
array('name' => 'Gamma', 'price' => '14'),
array('name' => 'delta', 'price' => '16'),
array('name' => 'Epsilon', 'price' => '18'),
array('name' => 'zeta', 'price' => '20'),
...
);
# Create array of field to sort by - 'name' in this example
foreach ($PDOresult as $key => $row) {
$sort_by[$key] = $row['name'];
}
# Sort array - The flags SORT_NATURAL & SORT_FLAG_CASE are required to make the
# sorting case insensitive.
array_multisort($sort_by, SORT_ASC, SORT_NATURAL|SORT_FLAG_CASE, $PDOresult);
# Output
var_dump($PDOresult);
If using php 5.5+ you can skip the foreach() and use array_column() instead. Like so:
$sort_by = array_column($PDOresult, 'name');
I was tempted to edit this into the well written answer: How can I sort arrays and data in PHP? but I didn't want to screw up the formatting so if someone wants to do that and close this, that would be fine with me.
Comments
@damndaewoo
SORT_ASC|SORT_NATURAL|SORT_FLAG_CASE
Will give you in some case :
Warning: array_multisort(): Argument #2 is an unknown sort flag
As the documentation say here you should use ',' instead of '|' But you CANNOT do the following :
SORT_ASC,SORT_NATURAL,SORT_FLAG_CASEBecause you will get an unexpected :
Argument #4 is expected to be an array or sorting flag that has not already been specified
instead you are going to use both technics as follow :
array_multisort($sort_by, SORT_ASC,SORT_NATURAL|SORT_FLAG_CASE, $PDOresult);
1 Comment
damndaewoo
I have not struck this warning before and I've been using this method for some time now. I'm guessing it depends on your configuration
You could also simply do this:
foreach ($PDOresult as $key => $row) {
$sort_by[$key] = strtolower($row['name']);
}
array_multisort($sort_by, SORT_ASC, $PDOresult);
No special flags are needed as everything that is sorted by is lower case. If you are worried about UTF-8, use mb_strtolower() instead. This will have the same result as the solution with the special flags, but is in my opinion more intuitive.
