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Showing content from http://www.arrayfire.org/docs/machine_learning_2deep_belief_net_8cpp-example.htm below:

ArrayFire: machine_learning/deep_belief_net.cpp

#include <math.h>

#include <stdio.h>

#include <string>

#include <vector>

#include "mnist_common.h"

using std::vector;

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 rbm {

private:

public:

rbm(int v_size, int h_size)

: weights(

randu

(h_size, v_size) / 100.f)

}

void

train(

const array

&in,

double

lr,

int

num_epochs,

int

batch_size,

bool verbose) {

const int

num_samples = in.

dims

(0);

const int num_batches = num_samples / batch_size;

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

double err = 0;

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

int st = j * batch_size;

int en = std::min(num_samples - 1, st + batch_size - 1);

int num = en - st + 1;

array

h_pos = sigmoid_binary(

tile

(h_bias, num) +

sigmoid_binary(

tile

(v_bias, num) +

matmul

(h_pos, weights));

array

h_neg = sigmoid_binary(

tile

(h_bias, num) +

array

delta_w = lr * (c_pos - c_neg) / num;

array

delta_vb = lr *

sum

(v_pos - v_neg) / num;

array

delta_hb = lr *

sum

(h_pos - h_neg) / num;

weights += delta_w;

v_bias += delta_vb;

h_bias += delta_hb;

if (verbose) { err += error(v_pos, v_neg); }

}

if (verbose) {

printf("Epoch %d: Reconstruction error: %0.4f\n", i + 1,

err / num_batches);

}

}

}

}

};

class dbn {

private:

const int in_size;

const int out_size;

const int num_hidden;

const int num_total;

std::vector<array> weights;

std::vector<int> hidden;

}

vector<array> forward_propagate(

const array

&input) {

vector<array> signal(num_total);

signal[0] = input;

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

array

in = add_bias(signal[i]);

}

return signal;

}

void

back_propagate(

const

vector<array> signal,

const array

&target,

const double &alpha) {

array

out = signal[num_total - 1];

array

err = (out - target);

int

m = target.

dims

(0);

for (int i = num_total - 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)));

}

}

public:

dbn(const int in_sz, const int out_sz, const std::vector<int> hidden_layers)

: in_size(in_sz)

, out_size(out_sz)

, num_hidden(hidden_layers.size())

, num_total(hidden_layers.size() + 2)

, weights(hidden_layers.size() + 1)

, hidden(hidden_layers) {}

void

train(

const array

&input,

const array

&target,

double

lr_rbm = 1.0,

double lr_nn = 1.0, const int epochs_rbm = 15,

const int epochs_nn = 300, const int batch_size = 100,

double maxerr = 1.0, bool verbose = false) {

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

if (verbose) { printf("Training Hidden Layer %d\n", i); }

int visible = (i == 0) ? in_size : hidden[i - 1];

rbm r(visible, hidden[i]);

r.train(X, lr_rbm, epochs_rbm, batch_size, verbose);

X = r.prop_up(X);

weights[i] = r.get_weights();

if (verbose) { printf("\n"); }

}

weights[num_hidden] =

0.05 *

randu

(hidden[num_hidden - 1] + 1, out_size) - 0.0025;

const int

num_samples = input.

dims

(0);

const int num_batches = num_samples / batch_size;

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

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

int st = j * batch_size;

int en = std::min(num_samples - 1, st + batch_size - 1);

vector<array> signals = forward_propagate(x);

array

out = signals[num_total - 1];

back_propagate(signals, y, lr_nn);

}

int st = (num_batches - 1) * batch_size;

int en = num_samples - 1;

array

out = predict(input(

seq

(st, en), span));

double

err = error(out, target(

seq

(st, en), span));

if (err < maxerr) {

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

return;

}

if (verbose) {

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

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

}

}

}

vector<array> signal = forward_propagate(input);

array

out = signal[num_total - 1];

return out;

}

};

int dbn_demo(bool console, int perc) {

printf("** ArrayFire DBN 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);

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(100);

layers.push_back(50);

dbn network(train_feats.

dims

(1), num_classes, layers);

timer::start();

network.train(train_feats, train_target,

0.2,

4.0,

15,

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;

try {

return dbn_demo(console, perc);

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

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 matmulTN(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 array matmulNT(const array &lhs, const array &rhs)

C++ Interface to multiply two matrices.

AFAPI array transpose(const array &in, const bool conjugate=false)

C++ Interface to transpose a matrix.

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 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 tile(const array &in, const unsigned x, const unsigned y=1, const unsigned z=1, const unsigned w=1)

C++ Interface to generate a tiled array.

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

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

AFAPI array sum(const array &in, const int dim=-1)

C++ Interface to sum array elements over a given dimension.


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