Sort Array By Values

[rascle]

Hi

 

I have an array (which is an equation) lets say it is

Array ( [0] => 18x [1] => 10x^2 [2] => 17 )

 

I want to order the array in terms of the value after ^, so that the highest values after ^ are grouped first. Therefore the above array I want it sorted to become

Array ( [0] => 10x^2 [1] => 18x [2] => 17 )

Does anyone have any idea how I would sort it? I have tried using php sort() to no avail.

 

Thanks,

 

Rhys

Edited November 19, 2012 by Zane

[rascle]

I havent got a solution but I can change the values so that x is x^1 and a constant is x^0. This might make it easier, all I need to know is how to order based on the value after "x^"

[Barand]

You would have to usort() with a custom function

[rascle]

But what would the function be?

[Barand]

What have you got so far?

Edited November 19, 2012 by Barand

[rascle]

Using the php.net I have come up with the following, but it is probably rubbish!:

 

function sortdtr($a,$B){
$a = explode('x^',$a);
$b = explode('x^',$B);
if($a==$B){ return 0; }
else if($a>$B){ return -1;}
else if($a<$B){ return 1; }

}

usort($dtr, "sortdtr");
echo "<br/>";
print_r($dtr);

Edited November 19, 2012 by Zane

[rascle]

But it isn't listing them how I want it, I'll have to do some more research unless you have any insights?

[Barand]

You aren't comparing the exponent values, just the arrays. You need to compare $a[1] with $b[1] after exploding.

 

There will also be items without "x^"

[rascle]

Solved, thank you