[RESOLVED] MATH GENIUS? - How to calculate equal increments for filtering by price...

[iceomnia]

Okay I know this is going to be a tough one, so I'll warn you now!

I want to achieve this:

[B]By Price[/B]
    up to £449
    £450 - £1,339
    £1,340 - £3,119
    £3,120 - £6,689
    £6,690 or more

I could hard code this, but the prblem is that I want it to do the following:

I will select a MIN and MAX price from the database as follows:

list($minprice, $maxprice) = mysql_fetch_row(mysql_query("SELECT MIN(price) AS lowest_price, MAX(price) AS highest_price FROM product_table "));

(Don't wory about syntax errors - thanks, but that's not important right now)

So I have 2 variables, $minprice & $maxprice.

I want SIX equal increments, the $minprice COULD be 0.00 and the last price option NEEDS to be less than the $maxprice because I need to be able to say "£5,599 or more".

So logically if I have a prices available between £399 and £6,999 the following would be my result:

[B]By Price[/B]
    up to £449
    £450 - £1,339
    £1,340 - £3,119
    £3,120 - £6,689
    £6,650 or more

£0.00 to £329, this:

[B]By Price[/B]
    £0 -  £50
    £100 - £150
    £150 - £200
    £200 - £250
    £300 or more

And, £0.00 to £49, this:

[B]By Price[/B]
    £0 -  £10
    £10 - £25
    £25 - £40
    £40 or more

And, £0.00 to £0.49, this:

[B]By Price[/B]
    £0 -  £0.10
    £0.10 - £0.25
    £0.25 - £0.40
    £0.40 or more

So as you can see, a maximum of 6 increments, but if you can't fit them in then It may be appropriate to reduce them to 4 (for example).

Anyone done anything like this before?

Thanks in advance :-)

[iceomnia]

Hey, come on guys: Someone must have done this before?

[NogDog]

I'm not sure a math genius is required. What is needed is some sort of understanding of the precise logic you want to implement. For instance, what determines whether there should be 4, 5, or 6 increments? What if the minimum was 999 and the maximum 1099: do I make some lower-priced increments that would be below the minimum? And in that 999-1099 example, what determines whether the top increment should be "900 or more", "950 or more", "1000 or more", or "1050 or more"?

Chance are that once you figure out what the "rules" actually are, the code will essentially write itself. But it will be hard for us to write it for you until we know what the rules are.

[coldwerturkey]

this would work for some of your examples, but not for others...

<?php

function rounddown($num) {
	$count = strlen($num);
	if ($count > 1) {
		$zeros = '';
		for ($i = 1; $i <= $count-1; $i++) {
    		$zeros .= 0;
		}
		$num = substr_replace($num, $zeros, 1, $count);
	}
	return $num;
}


$highest = rounddown(799);
$lowest = 0;

$difference = $highest-$lowest;

$amount_between = ceil($difference/6);

$price_to = $lowest+$amount_between;


$i = 1;
while ($price_to < $highest) {
	if ($lowest == 0) {
		echo "up to ".$price_to."<br />";
	}
	elseif ($i == 5) {
		echo $lowest." or more <br />";	
	}
	else {
		echo $lowest." - ".$price_to."<br />";
	}

$i++;
$price_to 	= $price_to + $amount_between;
$lowest 	= $lowest + $amount_between;
}
?>

take from it what you can, it only solves a few of your requests...

[iceomnia]

So I slightly modified it:

<?php

function rounddown($num)
{
    $count = strlen($num);

if ($count > 1)
{
    $zeros = '';
    for ($i = 1; $i <= $count-1; $i++)
	{
        $zeros .= 0;
    }

	$num = substr_replace($num, $zeros, 1, $count);
}

return $num;
}

function findprices($low=0, $high=0, $increments=6)
{
	// Fix
	//$increments;

// Highest Price
$highest = rounddown($high);

// Lowest Price
$lowest = $low;

$difference = $highest-$lowest;

$amount_between = ceil($difference/$increments);

$price_to = $lowest+$amount_between;


$i = 1;
$output = array();
while ($price_to < $highest)
{
	if ($lowest == 0)
	{
		$output[$i]['text'] = "up to ".$price_to;
		$output[$i]['link'] = "/search.php?pf=0&&pt=".$price_to;
	}
	elseif ($i == $increments-1)
	{
		$output[$i]['text'] = $lowest." or more";
		$output[$i]['link'] = "/search.php?pf=".$lowest."&pt=9000000";
	}
	else
	{
		$output[$i]['text'] = $lowest." - ".$price_to;
		$output[$i]['link'] = "/search.php?pf=".$lowest."&pt=".$price_to;
	}

	$i++;
	$price_to     = $price_to + $amount_between;
	$lowest     = $lowest + $amount_between;
}

return array_values($output);
}


?>

<?php 

$prices = findprices(0, 200, 6);

print_r($prices); ?>

And it gives me an array to do whatever I like with!

Array
(
    [0] => Array
        (
            [text] => up to 34
            [link] => /search.php?pf=0&&pt=34
        )

[1] => Array
    (
        [text] => 34 - 68
        [link] => /search.php?pf=34&pt=68
    )

[2] => Array
    (
        [text] => 68 - 102
        [link] => /search.php?pf=68&pt=102
    )

[3] => Array
    (
        [text] => 102 - 136
        [link] => /search.php?pf=102&pt=136
    )

[4] => Array
    (
        [text] => 136 or more
        [link] => /search.php?pf=136&pt=9000000
    )

)

Thanks guys, you've been a great help!