Reducing the size of JSON objects

Question

I wrote a function to reduce the size of JSON objects that works simply by turning every associative array into an indexed one, and moving each property's name to the first row of the data array (ordering it a bit like a CSV file, I guess).

<?php

/**
 * Converts a list of associative arrays into indexed arrays.
 *
 * Each property name is collated within an extra array inserted at the beginning
 * of the returned array, structuring the data in a CSV-like fashion. For example:
 *
 *   array(
 *       array('first_name' => 'John',   'last_name' => 'Gardner',   'age' => 28),
 *       array('first_name' => 'Sum',    'last_name' => 'Kunt',      'age' => 25)
 *   )
 *
 * Would be returned as:
 *
 *   array(
 *       array('first_name', 'last_name',    'age'),
 *       array('John',       'Gardner',      28),
 *       array('Sum',        'Kunt',         25)
 *   )
 *
 * Properties are indexed in the order they're encountered when traversing the original data
 * list, with any missing properties assigned empty values if they're present in some rows
 * but absent in others. For instance, consider the following inconsistent data structure,
 * with two rows sharing only partial similarity:
 *
 *   array(
 *       array('first_name' => 'John',   'age' =>  28),
 *       array('first_name' => 'Sum',    'dob' => '1990-08-20')
 *   )
 *
 * These would be collated and returned as:
 *
 *   array(
 *       array('first_name',   'age',    'dob'),
 *       array('John',         '28',      NULL),
 *       array('Sum',           NULL,    '1990-08-20')
 *   )
 *
 * This ensures data will be ordered in a consistent format, and can help reduce latency
 * and bandwidth costs when sending large payloads of JSON-encoded data.
 *
 * @param array $data - A multidimensional array to operate upon
 * @return array
 */
function collate_arrays($data){
    $output     =   array();

    # First, cycle through each row to extract a list of every unique field name that's present.
    $fields     =   array();
    $count      =   0;

    foreach($data as $row){
        foreach($row as $name => $value)
            if(!isset($fields[$name]))
                $fields[$name]  =   $count++;
    }


    # Flip the list of field names and store them in the first row of the returned array.
    $fields     =   array_flip($fields);
    $output[]   =   $fields;


    # Next, run through the array again, ensuring every array and its properties are consistently indexed in running field order.
    foreach($data as $row){
        $indexed_row = array();

        for($i = 0; $i < $count; ++$i)
            $indexed_row[$i] = $row[$fields[$i]];

        $output[]   =   $indexed_row;
    }

    return $output;
}


# Sample use below (with a particularly extreme example)
$messy_array    =   array(
    array('last_name'   => 'Gardner',  'first_name' => 'John',         'dob'           => '1987-04-18',    'age'       =>   28),
    array('first_name'  => 'John',     'last_name'  => 'Gardner',      'age'           =>  28,             'dob'       =>  '1987-04-18'),
    array('first_name'  => 'John',     'last_name'  => 'Gardner',      'age'           =>  28,             'dob'       =>  '1987-04-18'),
    array('first_name'  => 'John',     'last_name'  => 'Gardner',      'age'           =>  28,             'dob'       =>  '1987-04-18'),
    array('age'         =>  28,        'dob'        => '1987-04-18',   'first_name'    => 'John',          'last_name' =>  'Gardner'),
    array(
        'txtFirstName'  => 'John',
        'last_name'     => 'GARDNER',
        'txtLastName'   => 'Gardner',
        'txtAge'        =>  28,
        'dobYear'       =>  1987,
        'dobMonth'      =>  4,
        'dobDay'        =>  18
    ),
    array('first_name'  =>  'John',     'last_name' =>  'Gardner',     'age'    =>  28,     'dob'   => '1987-04-18'),
    array('first_name'  =>  'John',     'last_name' =>  'Gardner',     'age'    =>  28,     'dob'   => '1987-04-18'),
    array('first_name'  =>  'John',     'last_name' =>  'Gardner',                          'dob'   => '1987-04-18'),
    array('first_name'  =>  'John',     'last_name' =>  'Gardner',     'age'    =>  28)
);



header('Content-Type: text/plain; charset=UTF-8');
error_reporting(E_ALL ^ E_NOTICE);

$sorted =   collate_arrays($messy_array);
print_r($sorted);

It works perfectly fine: my issue is I'm not sure I've described the function's purpose clearly enough, or even given it a descriptive-enough name. I've been hit with writer's block so badly, I spent ages writing and rewriting the function's doc-block with no satisfaction.

I'm also worried I might've over-elaborated on the function's purpose, which I had trouble avoiding given its specific nature.

Is there anything unclear, misleading or just plain weird about this function or what it does? I hope I'm just going crazy from looking at my own code for too long...

Answer 1

The docs looks GOOD to me, it explains and provides an example of how to use it, so it will be quite easy to anyone use it and achieve what is needed.

You explain each main blocks with a comment, and avoid overcommenting, what is good, so, commenting in my opinion is really well done.

The only issues I see here are not related with doc, but with the code format and the fact you don't write any brace on one line block loops.

• Code format: When coding, try to attach to a format, for example PSR-2, follow a standard will help you to share the code and make sure that anybody has the same way to follow it. You can read more on it in https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md.
• Writing Braces: Your loops structures lack braces in one line blocks of code. Whilst this (of course) will work, may lead to horrible situations later, if you, for example are in a hurry and write a second line without realizing. The second line will be always applied out of the if or just one if it's a for. Is a good practice ALWAYS open and close your loops, even if they are a one-line loop blocks.