Is there a "map" function in php?

Question

I am trying to find a php equivalent of processing's "map" function so I can re-map a number from one range to another. Does anything exist? Is it called something different?

http://processing.org/reference/map_.html

For example to map a value from 0-100 to 0-9.

map(75, 0, 100, 0, 9);

Answer 1

There is no native function for doing this, but it's easy to create:

function map($value, $low1, $high1, $low2, $high2) {
    return ($value / ($high1 - $low1)) * ($high2 - $low2) + $low2;
}

This is untested, but you should hopefully get the idea.

Answer 2

Thanks for this great function!

I would personally improve a bit this function by adding simple error checking, to avoid dividing by 0, which would make PHP have a fatal error.

function map($value, $low1, $high1, $low2, $high2) {
    if ($low1 == $high1)
         return $low1;

    return ($value / ($high1 - $low1)) * ($high2 - $low2) + $low2;
}