def model_using_sgd(X,
Y,
layers_dims,
learning_rate=0.01,
initialization='random',
_lambda=0,
keep_prob=1,
init_const=0.01,
num_of_iterations=10000,
print_cost=True,
print_cost_after=1000,
seed=None):
L = len(layers_dims) - 1 # number of layers
m = X.shape[1] # number of training examples
# Initialize parameters
parameters = initialize_parameters(layers_dims, initialization, init_const,
seed)
# Gradient Descent
for i in range(num_of_iterations):
for j in range(m):
# Forward propagation
if keep_prob == 1:
AL, caches = forward_propagation(X[:, j], parameters, L)
elif keep_prob < 1:
AL, caches = forward_propagation_with_dropout(
X[:, j], parameters, L, keep_prob)
# Compute cost
if _lambda == 0:
cost = compute_cost(AL, Y[:, j])
else:
cost = compute_cost_with_regularization(
AL, Y[:, j], parameters, _lambda, L)
# Backward propagation
if _lambda == 0 and keep_prob == 1:
grads = backward_propagation(AL, Y[:, j], caches)
elif _lambda != 0:
grads = backward_propagation_with_regularization(
AL, Y[:, j], caches, _lambda)
elif keep_prob < 1:
grads = backward_propagation_with_dropout(
AL, Y[:, j], caches, keep_prob)
# Updating parameters
parameters = update_parameters_using_gd(parameters, grads,
learning_rate, L)
# Priniting cost after given iterations
if print_cost and i % print_cost_after == 0:
print("Cost after iteration %i: %f" % (i, cost))
# Gradient checking
gradient_checking(parameters, grads, X, Y, layers_dims, _lambda=_lambda)
return parameters
def model(X,
Y,
layers_dims,
learning_rate=0.01,
optimizer='adam',
beta=0.9,
beta1=0.9,
beta2=0.999,
epsilon=1e-8,
mini_batch_size=64,
initialization='random',
_lambda=0,
keep_prob=1,
init_const=0.01,
num_of_iterations=10000,
print_cost=True,
print_cost_after=1000):
L = len(layers_dims) - 1 # number of layers
costs = [] # to keep track of total cost
seed = 10 # For grading purposes, so that your "random" minibatches are the same as ours
t = 0 # initializing the counter required for Adam update
m = X.shape[1] # number of training example
# Initialize parameters
parameters = initialize_parameters(layers_dims, initialization, init_const,
seed)
# Initialize the optimizer
if optimizer == 'gd':
pass # no initialization required for gradient descent
elif optimizer == 'momentum':
v = initialize_velocity(parameters, L)
elif optimizer == 'adam':
v, s = initialize_adam(parameters, L)
# Optimization loop
for i in range(num_of_iterations):
# Define the random minibatches. We increment the seed to reshuffle differently the dataset after each epoch
seed = seed + 1
mini_batches = random_mini_batches(X, Y, mini_batch_size, seed)
cost_total = 0
for mini_batch in mini_batches:
# Select a minibatch
(minibatch_X, minibatch_Y) = mini_batch
# Forward propagation
if keep_prob == 1:
AL, caches = forward_propagation(minibatch_X, parameters, L)
elif keep_prob < 1:
AL, caches = forward_propagation_with_dropout(
minibatch_X, parameters, L, keep_prob)
# Compute cost and add to the total cost
if _lambda == 0:
cost_total += compute_cost(AL, minibatch_Y)
else:
cost_total += compute_cost_with_regularization(
AL, minibatch_Y, parameters, _lambda, L)
# Backward propagation
if _lambda == 0 and keep_prob == 1:
grads = backward_propagation(AL, minibatch_Y, caches)
elif _lambda != 0:
grads = backward_propagation_with_regularization(
AL, minibatch_Y, caches, _lambda)
elif keep_prob < 1:
grads = backward_propagation_with_dropout(
AL, minibatch_Y, caches, keep_prob)
# Update parameters
if optimizer == 'gd':
parameters = update_parameters_using_gd(
parameters, grads, learning_rate, L)
elif optimizer == 'momentum':
parameters, v = update_parameters_using_momentum(
parameters, grads, v, beta, learning_rate, L)
elif optimizer == 'adam':
t += 1 # adam counter
parameters, v, s = update_parameters_using_adam(
parameters, grads, v, s, t, learning_rate, L, beta1, beta2,
epsilon)
cost_avg = cost_total / m
# Print the cost every given epoch
if print_cost and i % print_cost_after == 0:
print("Cost after epoch %i: %f" % (i, cost_avg))
if print_cost and i % 100 == 0:
costs.append(cost_avg)
# Gradient checking
gradient_checking(parameters,
grads,
X,
Y,
layers_dims,
_lambda=_lambda)
return parameters