Converting Python Code to PHP

Question

Is there a software converter out there that can automatically convert this python code to PHP?

#!/usr/bin/python
import math

def calcNumEntropyBits(s):
        if len(s) <= 0: return 0.0
        symCount = {}
        for c in s:
                if c not in symCount: symCount[c] = 1
                else: symCount[c] += 1
        entropy = 0.0
        for c,n in symCount.iteritems():
                prob = n / float(len(s))
                entropy += prob * (math.log(prob)/math.log(2))
        if entropy >= 0.0: return 0.0
        else: return -(entropy*len(s))

def testEntropy(s):
        print "Bits of entropy in '%s' is %.2f" % (s, calcNumEntropyBits(s))

testEntropy('hello world')
testEntropy('bubba dubba')
testEntropy('aaaaaaaaaaa')
testEntropy('aaaaabaaaaa')
testEntropy('abcdefghijk')

Answer 1

I'm not aware of any Python-to-PHP converter in the wild, but it should be a trivial task to port and the similarities are quite easy to spot:

function calcNumEntropyBits($s) {
        if (strlen($s) <= 0) return 0.0;
        $symCount = array();
        foreach (str_split($s) as $c) {
                if (!in_array($c,$symCount)) $symCount[$c] = 1;
                else $symCount[$c] ++;
        }
        $entropy = 0.0;
        foreach ($symCount as $c=>$n) {
                $prob = $n / (float)strlen($s);
                $entropy += $prob * log($prob)/log(2);
        }
        if ($entropy >= 0.0) return 0.0;
        else return -($entropy*strlen($s));
}

function testEntropy($s):
        printf("Bits of entropy in '%s' is %.2f",$s,calcNumEntropyBits($s));

testEntropy('hello world');
testEntropy('bubba dubba');
testEntropy('aaaaaaaaaaa');
testEntropy('aaaaabaaaaa');
testEntropy('abcdefghijk');

The last few lines in the first function could have also been written as a standard PHP ternary expression:

return ($entropy >= 0.0)? 0.0: -($entropy*strlen($s));

Answer 2

I created a python-to-php converter called py2php. It can auto-translate the basic logic and then you will need to tweak library calls, etc. Still experimental.

Here is auto-generated PHP from the python provided by the OP.

<?php
require_once('py2phplib.php');
require_once( 'math.php');
function calcNumEntropyBits($s) {
    if ((count($s) <= 0)) {
        return 0.0;
    }
    $symCount = array();
    foreach( $s as $c ) {
        if (!$symCount.__contains__($c)) {
            $symCount[$c] = 1;
        }
        else {
            $symCount[$c] += 1;
        }
    }
    $entropy = 0.0;
    foreach( $symCount->iteritems() as $temp_c ) {
        $prob = ($n / float(count($s)));
        $entropy += ($prob * (math::log($prob) / math::log(2)));
    }
    if (($entropy >= 0.0)) {
        return 0.0;
    }
    else {
        return -($entropy * count($s));
    }
}

function testEntropy($s) {
    pyjslib_printFunc(sprintf('Bits of entropy in \'%s\' is %.2f', new pyjslib_Tuple([$s, calcNumEntropyBits($s)])));
}

testEntropy('hello world');
testEntropy('bubba dubba');
testEntropy('aaaaaaaaaaa');
testEntropy('aaaaabaaaaa');
testEntropy('abcdefghijk');

It would not run correctly due to the math import and __contains__, but those would be easy enough to fix by hand.

Answer 3

I am about 1/2 way done making a PHP interpreter in Python and I can tell you flat out that there are literally dozens of major edge cases that play out to thousands of possibilities that would make it almost impossible to port Python to PHP. Python has a much more robust grammar then PHP while further foward in the language, Python's stdlib is probably one of the most advanced in comparison to any other language in it's class.

My recommendation is to take your question one step further back, to why do you need a set of Python based logic in PHP. Alternatives to attempting to port/translate your code could include subprocessing from PHP to Python, using Gearman to have Python do work in the backend while PHP handles view logic, or a much more involved solution would be to implement a service bus or message queue between a PHP application and Python services.

PS. Apologies for any readability issues, finishing a 2 day sprint just now.

Answer 4

No such tool exists, you'll have to port the code yourself

Answer 5

I wondered myself that same question, and I found this PyToPhp.py file in the GitHubGist site. It is simple, and seem an start point for the begining.

I'm going to take a look to it!!!

Answer 6

I changed the library py2php from https://github.com/dan-da/py2php and forked it into a new repository at https://github.com/bunkahle/py2php You now can also use the python math library which is translated to PHP code. Still you have to do adaptations to your code in order to get it to work.