Breaking out one array into multiple arrays

Question

I am trying to make a simple roster which will rotate alphabetically.

I have a database with a list of 10 users sorted by column called First_Name. I am using PHP to retrieve all the names of people from the database and put them into an array alphabetically.

What I need to be able to do is create a further 4 arrays to list say 3 people in each array. I can get all the users in a single array by doing: $query = "SELECT * FROM carpark";

The arrays should always be filled with 3 people and when the number of people run out it should add people from the start of the loop to fill the gaps.

The way I have it right now, is to return the next 3 names from the database table which is probably not going to work if i want to rotate them.

I hope what I am asking for makes some sense..

Here is what I have so far:

<?php

include_once 'connect.php';

dbconnect("roster");

//=============================================
$w1_query = "SELECT * FROM carpark ORDER BY First_Name LIMIT 0,3";
$w1_result = mysqli_query($conn, $w1_query) or die("error getting data");

$w1_arr = array();
while ($w1_data = mysqli_fetch_array($w1_result, MYSQLI_ASSOC)) {
    array_push($w1_arr, $w1_data['First_Name']);
}
sort($w1_arr);
print_r($w1_arr);
//=============================================
//=============================================
$w2_query = "SELECT * FROM carpark ORDER BY First_Name LIMIT 3,5";
$w2_result = mysqli_query($conn, $w2_query) or die("error getting data");

$w2_arr = array();
while ($w2_data = mysqli_fetch_array($w2_result, MYSQLI_ASSOC)) {
    array_push($w2_arr, $w2_data['First_Name']);
}
sort($w2_arr);
//print_r($w2_arr);
//=============================================
//=============================================
$w3_query = "SELECT * FROM carpark ORDER BY First_Name LIMIT 6,8";
$w3_result = mysqli_query($conn, $w3_query) or die("error getting data");

$w3_arr = array();
while ($w3_data = mysqli_fetch_array($w3_result, MYSQLI_ASSOC)) {
    array_push($w3_arr, $w3_data['First_Name']);
}
sort($w3_arr);
//print_r($w3_arr);
//=============================================
//=============================================
$w4_query = "SELECT * FROM carpark ORDER BY First_Name LIMIT 9,11";
$w4_result = mysqli_query($conn, $w4_query) or die("error getting data");

$w4_arr = array();
while ($w4_data = mysqli_fetch_array($w4_result, MYSQLI_ASSOC)) {
    array_push($w4_arr, $w4_data['First_Name']);
}
sort($w4_arr);
//print_r($w4_arr);
//=============================================

//print_r($week1_arr);

echo '<table border=1><tr><th></th><th>week 1</th><th>week 2</th><th>week 3</th><th>week 4</th></tr>';

for ($x = 0; $x <= 2; $x++) {
echo '<tr><td>Bay '.$x.'</td><td>'.$w1_arr[$x].'</td><td>'.$w2_arr[$x].'</td><td>'.$w3_arr[$x].'</td><td>'.$w4_arr[$x].'</td></tr>';
}

echo '</table>';

?>

Here is the output of the above, as you can see the last two boxes should be filled with Chris, Eric.

Answer 1

it will be easy if creating a array as needed. Hope this will work. Array will generate according to the values assigning for $NoOfRows & $NoOfWeeks

$NoOfRows  = 3;
$NoOfWeeks = 4;
$totalLots = $NoOfRows * $NoOfWeeks;
$dataArr = array();

//fetch all persons
$query = "SELECT * FROM carpark ORDER BY First_Name";
$result = mysqli_query($conn, $query) or die("error getting data");
while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
    array_push($dataArr, $row['First_Name']);
}
$noOfPersons = count($dataArr);

//Create a new array with filling all lots
while ($noOfPersons < $totalLots) {
    $dataArr = array_merge($dataArr, $dataArr);
    $noOfPersons = count($dataArr);
}
$weekArr = array_chunk($dataArr , $NoOfRows);
//print the table
echo "<table border=1>";
for ($row = 0; $row < $NoOfRows; $row++) {
    if ($row == 0) {
        echo "<tr><td></td>";
        for ($col = 1; $col <= $NoOfWeeks; $col++) {
            echo "<td>Week $col</td>";
        }
        echo "</tr>";
    }
    for ($col = 0; $col < $NoOfWeeks; $col++) {
        if ($col == 0) {
            echo "<tr><td>Bay $row</td>";
        }
        echo "<td>";
        echo $weekArr[$col][$row];
        echo "</td>";
    }
    echo "</tr>";
}
echo "</table>";

Answer 2

Depending on the complexity of the system, you could merge http://php.net/manual/en/function.array-merge.php the result with itself then split it out with array_chunk http://php.net/manual/en/function.array-chunk.php.

$query = "SELECT * FROM carpark ORDER BY First_Name";
$result = mysqli_query($mysqli, $query) or die("error getting data");

$arr = array();
while ($data = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
    array_push($arr, $data['First_Name']);
}
sort($arr);

$combined=array_merge($arr,$arr);
$output=array_chunk($combined,3);

echo '<table border=1><tr><th></th><th>week 1</th><th>week 2</th><th>week 3</th><th>week 4</th></tr>';

for ($x = 0; $x <= 2; $x++) {
    echo '<tr><td>Bay '.$x.'</td><td>'.$output[0][$x].'</td>   <td>'.$output[1][$x].'</td><td>'.$output[2][$x].'</td><td>'.$output[3][$x].'</td></tr>';
}

echo '</table>';

Answer 3

Perhaps something like this, assuming you have all the names in a $names array, with numeric keys (required for desired functionality of array_merge).

$numBays = 3;
$numWeeks = 4;
$weeks = [];
$pool = [];
do {
    // Fill pool of names to a point where we have at least $numBays names
    while (count($pool) < $numBays) {
        $pool = array_merge($pool, $names);
    }
    // Extract an array containing $numBays names from the name pool
    $weeks[] = array_splice($pool, 0, $numBays);
} while(count($weeks) < $numWeeks);

This should leave you with a $weeks array, containing $numWeeks arrays, each with $numBays names, which you can then loop much like you currently do to produce your output.

for ($bay = 0; $bay < $numBays; $bay++) {
    echo '<tr><td>Bay '.$bay.'</td>';
    for ($week = 0; $week < $numWeeks; $week++) {
        echo '<td>'.$weeks[$week][$bay].'</td>';
    }
    echo '</tr>';
}