def nesterov(nn, X_train, y_train, val_set=None, alpha=1e-3, mb_size=256, n_iter=2000, print_after=100):
velocity = {k: np.zeros_like(v) for k, v in nn.model.items()}
gamma = .9
minibatches = get_minibatch(X_train, y_train, mb_size)
if val_set:
X_val, y_val = val_set
for iter in range(1, n_iter + 1):
idx = np.random.randint(0, len(minibatches))
X_mini, y_mini = minibatches[idx]
nn_ahead = copy.deepcopy(nn)
nn_ahead.model.update({k: v + gamma * velocity[k] for k, v in nn.model.items()})
grad, loss = nn_ahead.train_step(X_mini, y_mini)
if iter % print_after == 0:
if val_set:
val_acc = l.accuracy(y_val, nn.predict(X_val))
print('Iter-{} loss: {:.4f} validation: {:4f}'.format(iter, loss, val_acc))
else:
print('Iter-{} loss: {:.4f}'.format(iter, loss))
for layer in grad:
velocity[layer] = gamma * velocity[layer] + alpha * grad[layer]
nn.model[layer] -= velocity[layer]
return nn
def adam(nn, X_train, y_train, val_set=None, alpha=0.001, mb_size=256, n_iter=2000, print_after=100):
M = {k: np.zeros_like(v) for k, v in nn.model.items()}
R = {k: np.zeros_like(v) for k, v in nn.model.items()}
beta1 = .9
beta2 = .999
minibatches = get_minibatch(X_train, y_train, mb_size)
if val_set:
X_val, y_val = val_set
for iter in range(1, n_iter + 1):
t = iter
idx = np.random.randint(0, len(minibatches))
X_mini, y_mini = minibatches[idx]
grad, loss = nn.train_step(X_mini, y_mini)
if iter % print_after == 0:
if val_set:
val_acc = l.accuracy(y_val, nn.predict(X_val))
print('Iter-{} loss: {:.4f} validation: {:4f}'.format(iter, loss, val_acc))
else:
print('Iter-{} loss: {:.4f}'.format(iter, loss))
for k in grad:
M[k] = l.exp_running_avg(M[k], grad[k], beta1)
R[k] = l.exp_running_avg(R[k], grad[k]**2, beta2)
m_k_hat = M[k] / (1. - beta1**(t))
r_k_hat = R[k] / (1. - beta2**(t))
nn.model[k] -= alpha * m_k_hat / (np.sqrt(r_k_hat) + l.eps)
return nn
def rmsprop(nn, X_train, y_train, val_set=None, alpha=1e-3, mb_size=256, n_iter=2000, print_after=100):
cache = {k: np.zeros_like(v) for k, v in nn.model.items()}
gamma = .9
minibatches = get_minibatch(X_train, y_train, mb_size)
if val_set:
X_val, y_val = val_set
for iter in range(1, n_iter + 1):
idx = np.random.randint(0, len(minibatches))
X_mini, y_mini = minibatches[idx]
grad, loss = nn.train_step(X_mini, y_mini)
if iter % print_after == 0:
if val_set:
val_acc = l.accuracy(y_val, nn.predict(X_val))
print('Iter-{} loss: {:.4f} validation: {:4f}'.format(iter, loss, val_acc))
else:
print('Iter-{} loss: {:.4f}'.format(iter, loss))
for k in grad:
cache[k] = l.exp_running_avg(cache[k], grad[k]**2, gamma)
nn.model[k] -= alpha * grad[k] / (np.sqrt(cache[k]) + l.eps)
return nn
def sgd(nn, X_train, y_train, val_set=None, alpha=1e-3, mb_size=256, n_iter=2000, print_after=100):
minibatches = get_minibatch(X_train, y_train, mb_size)
if val_set:
X_val, y_val = val_set
for iter in range(1, n_iter + 1):
idx = np.random.randint(0, len(minibatches))
X_mini, y_mini = minibatches[idx]
grad, loss = nn.train_step(X_mini, y_mini)
if iter % print_after == 0:
if val_set:
val_acc = l.accuracy(y_val, nn.predict(X_val))
print('Iter-{} loss: {:.4f} validation: {:4f}'.format(iter, loss, val_acc))
else:
print('Iter-{} loss: {:.4f}'.format(iter, loss))
for layer in grad:
nn.model[layer] -= alpha * grad[layer]
return nn