PHP random colors for every row

Question

I'm using chart.js for making pie chart. I'd like to have different colors for every slice that the while loop generates.

$pull_request = 'SELECT * FROM `oc_aa_affiliatecollclicktracking`';
$sqli = $db->query($pull_request);

$num_rows=mysqli_num_rows($sqli);
$cur_row=0;
var pieData = [
                <?php 
                while ($row = mysqli_fetch_array($sqli)) {      
                $color=intval(256*$cur_row/($num_rows-1));
                $cur_row++;
                echo    '{
                            value: '.$row["product_clicks"].',
                            color: "rgb(256,'.$color.')", // NEED TO BE RANDOM FOR EVERY ROW/SLICE
                            highlight: "#333",
                            label: "' .$row["product_id"].'"
                            },';
                }
                ?>
                ];

                var ctx = document.getElementById("chart-area").getContext("2d");
                window.myPie = new Chart(ctx).Pie(pieData);

} );

what I found makes random colors that changes on page refresh for the whole chart but not for the individual slice. Any idea?

Answer 1

You can use rand() function to get random numbers in specific range. Take a look here

Example:

$color = "#" . rand(10,100);

you can replace $color wherever you want.

If you want hex colors use this function

function random_color(){
    mt_srand((double)microtime()*1000000);
    $c = '';
    while(strlen($c)<6){
        $c .= sprintf("%02X", mt_rand(0, 255));
    }
    return $c;
}

Answer 2

If you are wanting the colours to randomly change visibly you are going to want a javascript solution, or if you want each slice to be a different colour each time the page loads, you could use something similar to this?

<?php 

function randomColour() {
    // Found here https://css-tricks.com/snippets/php/random-hex-color/
    $rand = array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f');
    $color = '#'.$rand[rand(0,15)].$rand[rand(0,15)].$rand[rand(0,15)].$rand[rand(0,15)].$rand[rand(0,15)].$rand[rand(0,15)];
    return $color;
}

while ($row = mysqli_fetch_array($sqli)) {                  
    echo    '{
        value: '.$row["product_clicks"].',
        color: '.randomColour().', // NEED TO BE RANDOM FOR EVERY ROW/SLICE
        highlight: "#333",
        label: "' .$row["product_id"].'"
    },';
}
?>

If you need the javascript solution, it would be more complex, as I do not know what happens in the .Pie() constructor, and how you would hook a colour changing element into it