Question

How can I select a random set of rows

The important bits:

1. I need to specify the number of random rows to select via a variable.
2. Say for instance the number of rows I want to select is 10, then it HAS TO select 10 DIFFERENT rows. I don’t want it to pick out the same row a few times until it has 10.

The code below picks out 1 random row, how can I tailor this to the above spec?

<?php $rows = get_field('repeater_field_name');
$row_count = count($rows);
$i = rand(0, $row_count - 1);

echo $rows[$i]['sub_field_name']; ?>

Answer 1

<?php
    $rows = get_field('repeater_field_name');
    $row_count = count($rows);
    $rand_rows = array();

    for ($i = 0; $i < min($row_count, 10); $i++) {
        // Find an index we haven't used already (FYI - this will not scale
        // well for large $row_count...)
        $r = rand(0, $row_count - 1);
        while (array_search($r, $rand_rows) !== false) {
            $r = rand(0, $row_count - 1);
        }
        $rand_rows[] = $r;

        echo $rows[$r]['sub_field_name'];
    }
?>

This is a better implementation:

<?
$rows_i_want = 10;
$rows = get_field('repeater_field_name');

// Pull out 10 random rows
$rand = array_rand($rows, min(count($rows), $rows_i_want));

// Shuffle the array
shuffle($rand);                                                                                                                     

foreach ($rand as $row) {
    echo $rows[$row]['sub_field_name'];
}
?>