The PHP FANN (Fast Artificial Neural Network) Extension

This is a PHP binding for FANN (Fast Artificial Neural Network) library.

API

The API is documented on http://www.php.net/manual/en/book.fann.php where is the complete documentation for PHP FANN.

The API is very similar to the official FANN C API. Just functions for fixed fann_type have not been mapped because PHP always support float. In addition unnecessary arguments for some functions have been left out (for example array length that is not necessary for PHP arrays).

Installation

First download the source

git clone https://github.com/bukka/php-fann.git

Before you start installation make sure that libfann is installed on your system. It's part of the main repository in the most Linux distributions (search for fann). If not you need to install it first. Either download it from the official site or get it from your distro repository. For example in Fedora:

sudo yum install fann-devel

Then go to the created source directory and compile the extension. You need to have a php development package installed (command phpize must be available).

cd php-fann
phpize
./configure --with-fann
make
sudo make install

Finally you need to add

extension=fann.so

to the php.ini

Examples

These are just two basic examples for simple training and running supplied data on the trained network.

simple_train.php

$num_input = 2;
$num_output = 1;
$num_layers = 3;
$num_neurons_hidden = 3;
$desired_error = 0.001;
$max_epochs = 500000;
$epochs_between_reports = 1000;

$ann = fann_create_standard($num_layers, $num_input, $num_neurons_hidden, $num_output);

if ($ann) {
    fann_set_activation_function_hidden($ann, FANN_SIGMOID_SYMMETRIC);
    fann_set_activation_function_output($ann, FANN_SIGMOID_SYMMETRIC);

    $filename = dirname(__FILE__) . "/xor.data";
    if (fann_train_on_file($ann, $filename, $max_epochs, $epochs_between_reports, $desired_error))
        fann_save($ann, dirname(__FILE__) . "/xor_float.net");

    fann_destroy($ann);
}

simple_test.php

$train_file = (dirname(__FILE__) . "/xor_float.net");
if (!is_file($train_file))
    die("The file xor_float.net has not been created! Please run simple_train.php to generate it");

$ann = fann_create_from_file($train_file);
if (!$ann)
	die("ANN could not be created");

$input = array(-1, 1);
$calc_out = fann_run($ann, $input);
printf("xor test (%f,%f) -> %f\n", $input[0], $input[1], $calc_out[0]);
fann_destroy($ann);