Fill 2d array with rows for missing periods of array

Question

I have an array that contains periods from 1 - 13. Sometimes the array doesn't contain data for all periods and I need to fill in the missing ones, for example:

$array = [
    ['period' =>  7, 'y' => 20],
    ['period' =>  8, 'y' => 20.50],
    ['period' =>  9, 'y' => 7020],
    ['period' => 10, 'y' => 6520],
    ['period' => 11, 'y' => 65920],
    ['period' => 12, 'y' => 62820],
    ['period' => 13, 'y' => 6120],
];

For this case I need to run a php loop to fill in the missing first 6 periods with 0 y values. I've tried a variety of loops but with no joy.

Desired output:

[
    ['period' =>  1, 'y' => 0],
    ['period' =>  2, 'y' => 0],
    ['period' =>  3, 'y' => 0],
    ['period' =>  4, 'y' => 0],
    ['period' =>  5, 'y' => 0],
    ['period' =>  6, 'y' => 0],
    ['period' =>  7, 'y' => 20],
    ['period' =>  8, 'y' => 20.50],
    ['period' =>  9, 'y' => 7020],
    ['period' => 10, 'y' => 6520],
    ['period' => 11, 'y' => 65920],
    ['period' => 12, 'y' => 62820],
    ['period' => 13, 'y' => 6120],
]

Answer 1

You can get good semantics with using the standard array methods. For example:

<?php
$in = [
    ['period' =>  7, 'y' => 20],
    ['period' =>  8, 'y' => 20.50],
    ['period' =>  9, 'y' => 7020],
    ['period' => 10, 'y' => 6520],
    ['period' => 11, 'y' => 65920],
    ['period' => 12, 'y' => 62820],
    ['period' => 13, 'y' => 6120],
];

// collect available periods
$available = array_column($in, 'period');

// calculate missing periods
$missing = array_diff(range(1, 13), $available);

// transform missing to correct format
$addition = array_map(function ($period) { return ['period' => $period, 'y' => 0]; }, $missing);

// add missing to input
$out = array_merge($in, $addition);

// sort by period
usort($out, function ($a, $b) {
    return $a['period'] <=> $b['period'];
});

// done
print_r($out);

demo: https://3v4l.org/2fDYW