def model(X,
Y,
hidden_layers_dims,
learning_rate=1.2,
num_iter=5000,
hidden_activation='relu',
print_cost=True):
layers_dims = []
layers_dims.append(X_train.shape[0])
layers_dims.extend(hidden_layers_dims)
layers_dims.append(Y_train.shape[0])
parameters = initialize_parameters(layers_dims)
costs = []
for i in range(num_iter):
AL, caches = forward_propagation(X, parameters, hidden_activation)
cost = compute_cost(AL, Y)
dAL = compute_cost_derivative(AL, Y)
grads = backward_propagation(dAL, caches, hidden_activation)
parameters = update_parameters(parameters, grads, learning_rate)
if print_cost and i % 100 == 0:
print('Cost after iteration %d: %f' % (i, cost))
costs.append(cost)
# Plot Learning curve
plt.plot(costs)
plt.ylabel('Cost')
plt.xlabel('# of iterations (per 100)')
plt.title('Learning rate = ' + str(learning_rate))
plt.show()
# Plot Decision Boundary
print('decision boundary')
plot_decision_boundary(
lambda x: predict(x.T, parameters, hidden_activation), X, Y)
return parameters
# TODO: calculate the probability of a student being admitted with score of 45,85
# replace pred_prob = 0 with pred_prob = expression for that probability
pred_prob = theta_opt.dot(np.array([1, 45, 85]))
print "For a student with 45 on exam 1 and 85 on exam 2, the probability of admission = ", pred_prob
# compute accuracy on the training set
predy = log_reg1.predict(XX)
# TODO: calculate the accuracy of predictions on training set (hint: compare predy and y)
accuracy = 1. * sum([predy[i] == y[i] for i in xrange(len(y))]) / len(y)
print "Accuracy on the training set = ", accuracy
# plot the decision surface
plot_utils.plot_decision_boundary(X,y,theta_opt,'Exam 1 score', 'Exam 2 score',['Not Admitted','Admitted'])
plt.savefig('fig2.pdf')
# Compare with sklearn logistic regression
# note the parameters fed into the LogisticRegression call
from sklearn import linear_model
sk_logreg = linear_model.LogisticRegression(C=1e5,solver='lbfgs',fit_intercept=False)
sk_logreg.fit(XX,y)
print "Theta found by sklearn: ", sk_logreg.coef_
plot_utils.plot_decision_boundary_sklearn(X,y,sk_logreg,'Exam 1 score', 'Exam 2 score',['Not Admitted','Admitted'])
plt.savefig('fig2_sk.pdf')
def model(X,
Y,
hidden_layers_dims,
learning_rate,
num_epochs,
minibatch_size,
hidden_activation='relu',
lambd=0.0,
keep_prob=1.0,
optimizer='gd',
beta1=0.9,
beta2=0.999,
epsilon=1e-8,
print_cost=False,
show_plot=False):
layers_dims = []
layers_dims.append(X_train.shape[0])
layers_dims.extend(hidden_layers_dims)
layers_dims.append(Y_train.shape[0])
parameters = initialize_parameters(layers_dims)
if optimizer == 'momentum':
v = initialize_momentum(parameters)
if optimizer == 'adam':
v, s = initialize_adam(parameters)
costs = []
t = 0
seed = 10
for i in range(num_epochs):
seed = seed + 1
minibatches = hp.random_minibatches(X, Y, minibatch_size, seed)
for minibatch in minibatches:
(minibatch_X, minibatch_Y) = minibatch
AL, caches = forward_propagation(minibatch_X, parameters,
hidden_activation, keep_prob)
cost = compute_cost(AL, minibatch_Y, parameters, lambd)
dAL = compute_cost_derivative(AL, minibatch_Y)
grads = backward_propagation(dAL, caches, hidden_activation, lambd,
keep_prob)
if print_cost and keep_prob == 1.0 and i > 0 and i % 1000 == 0:
hp.grad_check(
lambda params: forward_prop_and_compute_cost(
minibatch_X, minibatch_Y, params, hidden_activation,
lambd, keep_prob), parameters, grads)
if optimizer == 'gd':
parameters = update_parameters(parameters, grads,
learning_rate)
elif optimizer == 'momentum':
parameters, v = update_parameters_momentum(
parameters, grads, v, learning_rate, beta1)
elif optimizer == 'adam':
t = t + 1
parameters, v, s = update_parameters_adam(
parameters, grads, v, s, t, learning_rate, beta1, beta2,
epsilon)
if print_cost and i % 100 == 0:
print('Cost after epoch %d: %f' % (i, cost))
costs.append(cost)
if show_plot:
# Plot Learning curve
plt.plot(costs)
plt.ylabel('Cost')
plt.xlabel('# of iterations (per 100)')
plt.title('Learning rate = ' + str(learning_rate))
plt.show()
# Plot Decision Boundary
print('Decision Boundary')
plot_decision_boundary(
lambda x: predict(x.T, parameters, hidden_activation), X, Y)
return parameters