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Showing content from http://www.arrayfire.org/docs/machine_learning_2neural_network_8cpp-example.htm below:

ArrayFire: machine_learning/neural_network.cpp

#include <math.h>

#include <stdio.h>

#include <string>

#include <vector>

#include "mnist_common.h"

using std::vector;

std::string toStr(

const dtype

dt) {

switch (dt) {

case f32

:

return "f32"

;

case f16

:

return "f16"

;

default: return "N/A";

}

}

float

accuracy(

const array

&predicted,

const array

&target) {

array

val, plabels, tlabels;

max(val, tlabels, target, 1);

max(val, plabels, predicted, 1);

return

100 * count<float>(plabels == tlabels) / tlabels.

elements

();

}

array

deriv(

const array

&out) {

return

out * (1 - out); }

double

error(

const array

&out,

const array

&pred) {

array

dif = (out - pred);

return sqrt

((

double

)(sum<float>(dif * dif)));

}

class ann {

private:

int num_layers;

vector<array> weights;

vector<array> forward_propagate(

const array

&input);

void

back_propagate(

const

vector<array> signal,

const array

&pred,

const double &alpha);

public:

ann(vector<int> layers,

double

range,

dtype

dt =

f32

);

double

train(

const array

&input,

const array

&target,

double

alpha = 1.0,

int max_epochs = 300, int batch_size = 100,

double maxerr = 1.0, bool verbose = false);

};

}

vector<array> ann::forward_propagate(

const array

&input) {

vector<array> signal(num_layers);

signal[0] = input;

for (int i = 0; i < num_layers - 1; i++) {

array

in = add_bias(signal[i]);

}

return signal;

}

void

ann::back_propagate(

const

vector<array> signal,

const array

&target,

const double &alpha) {

array

out = signal[num_layers - 1];

array

err = (out - target);

int

m = target.

dims

(0);

for (int i = num_layers - 2; i >= 0; i--) {

array

in = add_bias(signal[i]);

array

delta = (deriv(out) * err).T();

out = signal[i];

err = err(span,

seq

(1, out.

dims

(1)));

}

}

ann::ann(vector<int> layers,

double

range,

dtype

dt)

: num_layers(layers.size()), weights(layers.size() - 1), datatype(dt) {

std::cout

<< "Initializing weights using a random uniformly distribution between "

<< -

range

/ 2 <<

" and "

<<

range

/ 2 <<

" at precision "

<< toStr(datatype) << std::endl;

for (int i = 0; i < num_layers - 1; i++) {

if

(datatype !=

f32

) weights[i] = weights[i].

as

(datatype);

}

}

vector<array> signal = forward_propagate(input);

array

out = signal[num_layers - 1];

return out;

}

double

ann::train(

const array

&input,

const array

&target,

double

alpha,

int max_epochs, int batch_size, double maxerr, bool verbose) {

const int

num_samples = input.

dims

(0);

const int num_batches = num_samples / batch_size;

double err = 0;

for (int i = 0; i < max_epochs; i++) {

for (int j = 0; j < num_batches - 1; j++) {

int st = j * batch_size;

int en = st + batch_size - 1;

vector<array> signals = forward_propagate(x);

array

out = signals[num_layers - 1];

back_propagate(signals, y, alpha);

}

int st = (num_batches - 1) * batch_size;

int en = num_samples - 1;

array

out = predict(input(

seq

(st, en), span));

err = error(out, target(

seq

(st, en), span));

if (err < maxerr) {

printf("Converged on Epoch: %4d\n", i + 1);

return err;

}

if (verbose) {

if ((i + 1) % 10 == 0)

printf("Epoch: %4d, Error: %0.4f\n", i + 1, err);

}

}

return err;

}

int

ann_demo(

bool

console,

int

perc,

const dtype

dt) {

printf("** ArrayFire ANN Demo **\n\n");

array

train_images, test_images;

array

train_target, test_target;

int num_classes, num_train, num_test;

float frac = (float)(perc) / 100.0;

setup_mnist<true>(&num_classes, &num_train, &num_test, train_images,

test_images, train_target, test_target, frac);

train_images = train_images.

as

(dt);

test_images = test_images.

as

(dt);

train_target = train_target.

as

(dt);

}

int

feature_size = train_images.

elements

() / num_train;

array

train_feats =

moddims

(train_images, feature_size, num_train).

T

();

array

test_feats =

moddims

(test_images, feature_size, num_test).

T

();

train_target = train_target.

T

();

test_target = test_target.

T

();

vector<int> layers;

layers.push_back(train_feats.

dims

(1));

layers.push_back(100);

layers.push_back(50);

layers.push_back(num_classes);

ann network(layers, 0.05, dt);

timer::start();

network.train(train_feats, train_target,

2.0,

250,

100,

0.5,

true);

double train_time = timer::stop();

array

train_output = network.predict(train_feats);

array

test_output = network.predict(test_feats);

timer::start();

for (int i = 0; i < 100; i++) { network.predict(test_feats); }

double test_time = timer::stop() / 100;

printf("\nTraining set:\n");

printf("Accuracy on training data: %2.2f\n",

accuracy(train_output, train_target));

printf("\nTest set:\n");

printf("Accuracy on testing data: %2.2f\n",

accuracy(test_output, test_target));

printf("\nTraining time: %4.4lf s\n", train_time);

printf("Prediction time: %4.4lf s\n\n", test_time);

if (!console) {

test_output = test_output.

T

();

display_results<true>(test_images, test_output, test_target.

T

(), 20);

}

return 0;

}

int main(int argc, char **argv) {

int device = argc > 1 ? atoi(argv[1]) : 0;

bool console = argc > 2 ? argv[2][0] == '-' : false;

int perc = argc > 3 ? atoi(argv[3]) : 60;

if (perc < 0 || perc > 100) {

std::cerr << "Bad perc arg: " << perc << std::endl;

return EXIT_FAILURE;

}

std::string dts = argc > 4 ? argv[4] : "f32";

if (dts == "f16")

else if (dts != "f32") {

std::cerr << "Unsupported datatype " << dts << ". Supported: f32 or f16"

<< std::endl;

return EXIT_FAILURE;

}

std::cerr << "Half not available for device " << device << std::endl;

return EXIT_FAILURE;

}

try {

return ann_demo(console, perc, dt);

return 0;

}

A multi dimensional data container.

dim4 dims() const

Get dimensions of the array.

const array as(dtype type) const

Casts the array into another data type.

array T() const

Get the transposed the array.

dim_t elements() const

Get the total number of elements across all dimensions of the array.

An ArrayFire exception class.

virtual const char * what() const

Returns an error message for the exception in a string format.

seq is used to create sequences for indexing af::array

@ f32

32-bit floating point values

@ f16

16-bit floating point value

AFAPI array sigmoid(const array &in)

C++ Interface to evaluate the logistical sigmoid function.

AFAPI array sqrt(const array &in)

C++ Interface to evaluate the square root.

AFAPI array matmulTT(const array &lhs, const array &rhs)

C++ Interface to multiply two matrices.

AFAPI array matmul(const array &lhs, const array &rhs, const matProp optLhs=AF_MAT_NONE, const matProp optRhs=AF_MAT_NONE)

C++ Interface to multiply two matrices.

AFAPI void grad(array &dx, array &dy, const array &in)

C++ Interface for calculating the gradients.

array constant(T val, const dim4 &dims, const dtype ty=(af_dtype) dtype_traits< T >::ctype)

C++ Interface to generate an array with elements set to a specified value.

AFAPI array range(const dim4 &dims, const int seq_dim=-1, const dtype ty=f32)

C++ Interface to generate an array with [0, n-1] values along the seq_dim dimension and tiled across ...

AFAPI bool isHalfAvailable(const int device)

Queries the current device for half precision floating point support.

AFAPI void setDevice(const int device)

Sets the current device.

AFAPI void sync(const int device=-1)

Blocks until the device is finished processing.

AFAPI array join(const int dim, const array &first, const array &second)

C++ Interface to join 2 arrays along a dimension.

AFAPI array moddims(const array &in, const dim4 &dims)

C++ Interface to modify the dimensions of an input array to a specified shape.

AFAPI array randu(const dim4 &dims, const dtype ty, randomEngine &r)

C++ Interface to create an array of random numbers uniformly distributed.


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