How to select a random set of rows? - php

Question

How can I select a random set of rows
The important bits:
I need to specify the number of random rows to select via a variable.
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'];
}
?>

Answer 2

Simply loop through the random row process the number of random rows you want to get.
<?php
$rows_to_get=10;
$rows = get_field('repeater_field_name');
$row_count = count($rows);
$x=0
while($x<$rows_to_get){
echo $rows[rand(0, $row_count - 1)]['sub_field_name'];
$x++;
}
?>

Answer 3

You can give this a try
$rows = get_field('repeater_field_name');
var_dump(__myRand($rows, 10));
function __myRand($rows, $total = 1) {
$rowCount = count($rows);
$output = array();
$x = 0;
$i = mt_rand(0, $rowCount - 1);
while ( $x < $total ) {
if (array_key_exists($i, $output)) {
$i = mt_rand(0, $rowCount - 1);
} else {
$output[$i] = $rows[$i]['sub_field_name'];
$x ++;
}
}
return $output ;
}

Answer 4

A simple solution :
$rows = get_field('repeater_field_name');
$limit = 10;
// build new array
$data = array();
foreach ($rows as $r) { $data[] = $r['sub_field_name']; }
shuffle($data);
$data = array_slice($data, 0, min(count($data), $limit));
foreach ($data as $val) {
// do what you want
echo $val;
}