def test_output_linear_backward(self):
print_test("Testing linear backward function:")
np.random.seed(395)
x = np.random.randn(10, 2, 3)
w = np.random.randn(6, 5)
b = np.random.randn(5)
dout = np.random.randn(10, 5)
dx_num = eval_numerical_gradient_array(
lambda x: layers.linear_forward(x, w, b), x, dout)
dw_num = eval_numerical_gradient_array(
lambda w: layers.linear_forward(x, w, b), w, dout)
db_num = eval_numerical_gradient_array(
lambda b: layers.linear_forward(x, w, b), b, dout)
dx, dw, db = layers.linear_backward(dout, x, w, b)
dX_e = rel_error(dx_num, dx)
dW_e = rel_error(dw_num, dw)
db_e = rel_error(db_num, db)
print('dX relative error: ', dX_e)
print('dW relative error: ', dW_e)
print('db realtive error: ', db_e)
self.assertTrue(dX_e <= 5e-10)
self.assertTrue(dW_e <= 5e-10)
self.assertTrue(db_e <= 5e-10)
def test_output_linear_forward(self):
print_test("Testing linear forward function:")
n_X = 10
X_shape = [4, 2, 5]
n_out = 3
n_input = n_X * np.prod(X_shape)
n_weights = np.prod(X_shape) * n_out
X = np.linspace(-0.2, 0.5, num=n_input).reshape([n_X] + X_shape)
W = np.linspace(-0.4, 0.2, num=n_weights).reshape(
np.prod(X_shape), n_out)
b = np.linspace(0.5, 1, num=n_out)
# test
print ("n_input: ", n_input)
print ("n_weights: ", n_weights)
print ("X: ", X.shape, "\n", X)
print ("W: ", W.shape, "\n", W)
print ("b: ", b.shape, "\n", b)
out = layers.linear_forward(X, W, b)
correct_out = np.asarray([[1.33803627, 1.55459973, 1.7711632],
[1.04318148, 1.27389798, 1.50461448],
[0.7483267 , 0.99319623, 1.23806575],
[0.45347192, 0.71249447, 0.97151703],
[0.15861713, 0.43179272, 0.7049683],
[-0.13623765, 0.15109096, 0.43841958],
[-0.43109244, -0.12961079, 0.17187085],
[-0.72594722, -0.41031255, -0.09467787],
[-1.02080201, -0.6910143 , -0.3612266 ],
[-1.31565679, -0.97171605, -0.62777532]])
e = np.max(np.abs(correct_out - out))
e = rel_error(out, correct_out)
print("Relative difference", e)
self.assertTrue(e <= 5e-08)
def loss(self, X, y=None):
"""
Compute loss and gradient for a minibatch of data.
Args: print()
- X: Input data, numpy array of shape (N, d_1, ..., d_k)
- y: Array of labels, of shape (N,). y[i] gives the label for X[i].
Returns:
If y is None, then run a test-time forward pass of the model and
return:
- scores: Array of shape (N, C) giving classification scores, where
scores[i, c] is the classification score for X[i] and class c.
If y is not None, then run a training-time forward and backward pass
and return a tuple of:
- loss: Scalar value giving the loss
- grads: Dictionary with the same keys as self.param s, mapping
parameter
names to gradients of the loss with respect to those parameters.
"""
scores = None
X = X.astype(self.dtype)
linear_cache = dict()
relu_cache = dict()
dropout_cache = dict()
"""
TODO: Implement the forward pass for the fully-connected neural
network, compute the scores and store them in the scores variable.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
hidden_num = self.num_layers - 1
scores = X
cache_history = []
L2reg = 0
cache_history.append(scores)
#
for i in range(hidden_num):
scores = linear_forward(scores, self.params['W%d' % (i + 1)],
self.params['b%d' % (i + 1)])
cache_history.append(scores)
scores = relu_forward(scores)
cache_history.append(scores)
if self.use_dropout:
scores, cache = dropout_forward(scores,
self.dropout_params["p"],
self.dropout_params["train"],
self.dropout_params["seed"])
cache_history.append(cache)
L2reg += np.sum(self.params['W%d' % (i + 1)]**2)
i += 1
scores = linear_forward(scores, self.params['W%d' % (i + 1)],\
self.params['b%d' % (i + 1)])
L2reg += np.sum(self.params['W%d' % (i + 1)]**2)
L2reg *= 0.5 * self.reg
#######################################################################
# END OF YOUR CODE #
#######################################################################
# If y is None then we are in test mode so just return scores
if y is None:
return scores
loss, grads = 0, dict()
"""
TODO: Implement the backward pass for the fully-connected net. Store
the loss in the loss variable and all gradients in the grads
dictionary. Compute the loss with softmax. grads[k] has the gradients
for self.params[k]. Add L2 regularisation to the loss function.
NOTE: To ensure that your implementation matches ours and you pass the
automated tests, make sure that your L2 regularization includes a
factor of 0.5 to simplify the expression for the gradient.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
loss, dout = softmax(scores, y)
loss += L2reg
dout, grads['W%d' % (i + 1)], grads['b%d' % (i + 1)] = linear_backward(
dout, cache_history.pop(), self.params['W%d' % (i + 1)],
self.params['b%d' % (i + 1)])
grads['W%d' % (i + 1)] += self.reg * self.params['W%d' % (i + 1)]
i -= 1
while i >= 0:
if self.use_dropout:
dout = dropout_backward(dout, cache_history.pop())
dout = relu_backward(dout, cache_history.pop())
dout, grads['W%d' %
(i + 1)], grads['b%d' % (i + 1)] = linear_backward(
dout, cache_history.pop(),
self.params['W%d' % (i + 1)],
self.params['b%d' % (i + 1)])
grads['W%d' % (i + 1)] += self.reg * self.params['W%d' % (i + 1)]
i -= 1
#######################################################################
# END OF YOUR CODE #
#######################################################################
return loss, grads
def loss(self, X, y=None):
"""
Compute loss and gradient for a minibatch of data.
Args:
- X: Input data, numpy array of shape (N, d_1, ..., d_k)
- y: Array of labels, of shape (N,). y[i] gives the label for X[i].
Returns:
If y is None, then run a test-time forward pass of the model and
return:
- scores: Array of shape (N, C) giving classification scores, where
scores[i, c] is the classification score for X[i] and class c.
If y is not None, then run a training-time forward and backward pass
and return a tuple of:
- loss: Scalar value giving the loss
- grads: Dictionary with the same keys as self.params, mapping
parameter
names to gradients of the loss with respect to those parameters.
"""
scores = None
X = X.astype(self.dtype)
linear_cache = dict()
relu_cache = dict()
dropout_cache = dict()
"""
TODO: Implement the forward pass for the fully-connected neural
network, compute the scores and store them in the scores variable.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
inp = X
for i in range(1, self.num_layers):
W, b = self.params["W%d" % i], self.params["b%d" % i]
linOut = linear_forward(inp, W, b)
linear_cache["O%d" % i] = inp
reluOut = relu_forward(linOut)
relu_cache["O%d" % i] = linOut
inp = reluOut
if self.use_dropout:
dropOut, dropMask = dropout_forward(reluOut,
**self.dropout_params)
dropout_cache["O%d" % i] = dropMask
inp = dropOut
W, b = self.params["W%d" % (i + 1)], self.params["b%d" % (i + 1)]
scores = linear_forward(inp, W, b)
#######################################################################
# END OF YOUR CODE #
#######################################################################
# If y is None then we are in test mode so just return scores
if y is None:
return scores
loss, grads = 0, dict()
"""
TODO: Implement the backward pass for the fully-connected net. Store
the loss in the loss variable and all gradients in the grads
dictionary. Compute the loss with softmax. grads[k] has the gradients
for self.params[k]. Add L2 regularisation to the loss function.
NOTE: To ensure that your implementation matches ours and you pass the
automated tests, make sure that your L2 regularization includes a
factor of 0.5 to simplify the expression for the gradient.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
loss, dout = softmax(scores, y)
for k in range(1, self.num_layers + 1):
loss += 0.5 * self.reg * (self.params["W%d" % k]**2).sum()
dX, dW, db = linear_backward(dout, inp, W, b)
grads["W%d" % (i + 1)], grads["b%d" % (i + 1)] = dW + self.reg * W, db
for i in range(self.num_layers - 1, 0, -1):
if self.use_dropout:
dX = dropout_backward(dX, dropout_cache["O%d" % i],
**self.dropout_params)
reluBack = relu_backward(dX, relu_cache["O%d" % i])
W, b = self.params["W%d" % i], self.params["b%d" % i]
dX, dW, db = linear_backward(reluBack, linear_cache["O%d" % i], W,
b)
grads["W%d" % i], grads["b%d" % i] = dW + self.reg * W, db
#######################################################################
# END OF YOUR CODE #
#######################################################################
return loss, grads
def loss(self, X, y=None):
"""
Compute loss and gradient for a minibatch of data.
Args:
- X: Input data, numpy array of shape (N, d_1, ..., d_k)
- y: Array of labels, of shape (N,). y[i] gives the label for X[i].
Returns:
If y is None, then run a test-time forward pass of the model and
return:
- scores: Array of shape (N, C) giving classification scores, where
scores[i, c] is the classification score for X[i] and class c.
If y is not None, then run a training-time forward and backward pass
and return a tuple of:
- loss: Scalar value giving the loss
- grads: Dictionary with the same keys as self.params, mapping
parameter names to gradients of the loss with respect to those parameters.
"""
scores = None
X = X.astype(self.dtype)
linear_cache = dict()
relu_cache = dict()
dropout_cache = dict()
"""
TODO: Implement the forward pass for the fully-connected neural
network, compute the scores and store them in the scores variable.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
x_in = X
# If y is None then we are in test mode so just return scores
if y is None:
for i in range(1, self.num_layers):
linear_out = linear_forward(x_in, self.params['W' + str(i)], self.params['b' + str(i)])
relu_out = relu_forward(linear_out)
x_in = relu_out
logits = linear_forward(x_in, self.params['W' + str(self.num_layers)],
self.params['b' + str(self.num_layers)])
scores = softmax(logits, y)
# If y is not None then we are in train mode so just return scores
return scores
else:
self.last_grads_ = copy.deepcopy(self.grads_)
loss, grads = 0, dict()
self.grads_ = grads
for i in range(1, self.num_layers):
linear_out = linear_forward(x_in, self.params['W' + str(i)], self.params['b' + str(i)])
linear_cache["out" + str(i)] = linear_out
relu_out = relu_forward(linear_out)
relu_cache["out" + str(i)] = relu_out
dropout_out = relu_out
if self.use_dropout:
seed = 42 if self.dropout_params["seed"] is None else self.dropout_params["seed"]
dropout_out, mask = dropout_forward(relu_out, self.dropout_params["p"], True, seed)
dropout_cache["out" + str(i)] = dropout_out
dropout_cache["mask" + str(i)] = mask
x_in = dropout_out
logits = linear_forward(x_in, self.params['W' + str(self.num_layers)],
self.params['b' + str(self.num_layers)])
loss, dlogits = softmax(logits, y)
#######################################################################
# END OF YOUR CODE #
#######################################################################
# """
# TODO: Implement the backward pass for the fully-connected net. Store
# the loss in the loss variable and all gradients in the grads
# dictionary. Compute the loss with softmax. grads[k] has the gradients
# for self.params[k]. Add L2 regularisation to the loss function.
# NOTE: To ensure that your implementation matches ours and you pass the
# automated tests, make sure that your L2 regularization includes a
# factor of 0.5 to simplify the expression for the gradient.
# """
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
dout = dlogits
if self.use_dropout:
input_x = dropout_cache["out" + str(self.num_layers - 1)]
else:
input_x = relu_cache["out" + str(self.num_layers - 1)]
W = self.params['W' + str(self.num_layers)]
b = self.params['b' + str(self.num_layers)]
dout, dW, db = linear_backward(dout, input_x, W, b)
grads['W' + str(self.num_layers)] = dW
grads['b' + str(self.num_layers)] = db
for i in range(self.num_layers - 1, 1, -1):
if self.use_dropout:
mask = dropout_cache['mask' + str(i)]
dout = dropout_backward(dout, mask, seed, self.dropout_params["p"])
input_x = linear_cache["out" + str(i)]
dout = relu_backward(dout, input_x)
if self.use_dropout:
input_x = dropout_cache["out" + str(i - 1)]
else:
input_x = relu_cache["out" + str(i - 1)]
W = self.params['W' + str(i)]
b = self.params['b' + str(i)]
dout, dW, db = linear_backward(dout, input_x, W, b)
grads['W' + str(i)] = dW
grads['b' + str(i)] = db
if self.use_dropout:
mask = dropout_cache['mask' + str(1)]
dout = dropout_backward(dout, mask, seed,
self.dropout_params["p"])
input_x = linear_cache["out" + str(1)]
dout = relu_backward(dout, input_x)
W = self.params['W' + str(1)]
b = self.params['b' + str(1)]
dout, dW, db = linear_backward(dout, X, W, b)
grads['W' + str(1)] = dW
grads['b' + str(1)] = db
# add L2 regularisation
regularisation = 0.0
for i in range(1, self.num_layers + 1):
tempW = 0.5 * self.reg * np.square(self.params['W' + str(i)])
regularisation += np.sum(tempW)
grads['W' + str(i)] += self.reg * self.params['W' + str(i)]
loss += regularisation
#######################################################################
# END OF YOUR CODE #
#######################################################################
return loss, grads
def loss(self, X, y=None):
"""
Compute loss and gradient for a minibatch of data.
Args:
- X: Input data, numpy array of shape (N, d_1, ..., d_k)
- y: Array of labels, of shape (N,). y[i] gives the label for X[i]
Returns:
If y is None, then run a test-time forward pass of the model and
return:
- scores: Array of shape (N, C) giving classification scores, where
scores[i, c] is the classification score for X[i] and class c.
If y is not None, then run a training-time forward and backward pass
and return a tuple of:
- loss: Scalar value giving the loss
- grads: Dictionary with the same keys as self.params, mapping
parameter
names to gradients of the loss with respect to those parameters.
"""
scores = None
X = X.astype(self.dtype)
linear_cache = dict()
relu_cache = dict()
dropout_cache = dict()
"""
TODO: Implement the forward pass for the fully-connected neural
network, compute the scores and store them in the scores variable.
"""
if self.use_dropout:
self.dropout_params["train"] = False if y is None else True
Xi = linear_cache['0'] = X
if self.use_dropout:
p, t = self.dropout_params["p"], \
self.dropout_params["train"]
for i in range(self.num_layers):
W, b = self.params['W' + str(i + 1)], self.params['b' + str(i + 1)]
Xi = relu_cache[str(i)] = linear_forward(Xi, W, b)
if i != self.num_layers - 1:
Xi = linear_cache[str(i + 1)] = relu_forward(Xi)
if self.use_dropout:
# receive (out, mask)
Xi, dropout_cache[str(i)] = dropout_forward(Xi, \
p, t, None)
scores = Xi
# If y is None then we are in test mode, so just return scores
if y is None: return scores
loss, grads = 0, dict()
"""
TODO: Implement the backward pass for the fully-connected net. Store
the loss in the loss variable and all gradients in the grads
dictionary. Compute the loss with softmax. grads[k] has the gradients
for self.params[k]. Add L2 regularisation to the loss function.
NOTE: To ensure that your implementation matches ours and you pass the
automated tests, make sure that your L2 regularization includes a
factor of 0.5 to simplify the expression for the gradient.
"""
loss, dX = softmax(scores, y)
for i in reversed(range(self.num_layers)):
if i != self.num_layers - 1:
if self.use_dropout:
dX = dropout_backward(dX, \
dropout_cache[str(i)], p=p, train=t)
dX = relu_backward(dX, relu_cache[str(i)])
W, b = self.params['W' + str(i + 1)], self.params['b' + str(i + 1)]
dX, dW, db = linear_backward(dX, linear_cache[str(i)], W, b)
grads['W' + str(i + 1)], grads['b' + str(i + 1)] = \
dW + self.reg * self.params['W' + str(i + 1)], db
loss += 0.5 * self.reg * np.sum(W**2)
return loss, grads
def loss(self, X, y=None):
"""
Compute loss and gradient for a minibatch of data.
Args:
- X: Input data, numpy array of shape (N, d_1, ..., d_k)
- y: Array of labels, of shape (N,). y[i] gives the label for X[i].
Returns:
If y is None, then run a test-time forward pass of the model and
return:
- scores: Array of shape (N, C) giving classification scores, where
scores[i, c] is the classification score for X[i] and class c.
If y is not None, then run a training-time forward and backward pass
and return a tuple of:
- loss: Scalar value giving the loss
- grads: Dictionary with the same keys as self.params, mapping
parameter
names to gradients of the loss with respect to those parameters.
"""
scores = None
X = X.astype(self.dtype)
linear_cache = dict()
relu_cache = dict()
dropout_cache = dict()
"""
TODO: Implement the forward pass for the fully-connected neural
network, compute the scores and store them in the scores variable.
"""
# get num of hidden layers (do not count the output layer)
num_hidden_layers = self.num_layers - 1
# store the first layer's input in the linear cache
linear_cache[1] = X
# iterate through all layers, including the class layer
for i in range(1, self.num_layers + 1):
# compute this layer's W and b keys
Wkey, bkey = "W" + str(i), "b" + str(i)
# perform linear pass. output has dimensions M x N. Store it in relu_cache
relu_cache[i] = linear_forward(linear_cache[i], self.params[Wkey],
self.params[bkey])
# perform relu -> dropout
if i < self.num_layers:
# perform ReLU
relu_out = relu_forward(relu_cache[i])
# perform dropout
out, mask = dropout_forward(relu_out, \
self.dropout_params["p"], \
self.dropout_params["train"], \
self.dropout_params["seed"])
# add the mask to the dropout cache
dropout_cache[i] = mask
# cache this layer's output as input to the next layer in the linear cache
linear_cache[i + 1] = out
# final layer output is stored in the relu_cache since it did not go through dropout or ReLU
scores = relu_cache[self.num_layers]
# if y is None then we are in test mode so just return scores
if y is None:
return scores
"""
TODO: Implement the backward pass for the fully-connected net. Store
the loss in the loss variable and all gradients in the grads
dictionary. Compute the loss with softmax. grads[k] has the gradients
for self.params[k]. Add L2 regularisation to the loss function.
NOTE: To ensure that your implementation matches ours and you pass the
automated tests, make sure that your L2 regularization includes a
factor of 0.5 to simplify the expression for the gradient.
"""
# used to store gradients
grads = dict()
# perform softmax. should I log scores?
loss, dlogits = softmax(scores, y)
# used to store the upstream derivate of the next layer
dout = dlogits
for i in range(self.num_layers, 0, -1):
# compute this layer's W and b names
Wkey, bkey = "W" + str(i), "b" + str(i)
# add L2 regularisation. square each weight of this layer and add it to loss
loss += 0.5 * self.reg * np.sum(self.params[Wkey]**2)
if i < self.num_layers:
# perform dropout
dout = dropout_backward(dout, dropout_cache[i],
self.dropout_params["p"],
self.dropout_params["train"])
# perform ReLU
dout = relu_backward(dout, relu_cache[i])
# perform linear backward and store the gradients
dX, dW, db = linear_backward(dout, linear_cache[i],
self.params[Wkey], self.params[bkey])
# d(E_0 + 0.5 * reg * W_all^2)/dW_i = d(E_o)/dW_i + reg * W_i
# dW holds d(E_0/dW_i), so we must add the reg * W_i term ourselves
grads.update({Wkey: dW + self.reg * self.params[Wkey], bkey: db})
# set dout equal to dX
dout = dX
return loss, grads
def loss(self, X, y=None):
"""
Compute loss and gradient for a minibatch of data.
Args:
- X: Input data, numpy array of shape (N, d_1, ..., d_k)
- y: Array of labels, of shape (N,). y[i] gives the label for X[i].
Returns:
If y is None, then run a test-time forward pass of the model and
return:
- scores: Array of shape (N, C) giving classification scores, where
scores[i, c] is the classification score for X[i] and class c.
If y is not None, then run a training-time forward and backward pass
and return a tuple of:
- loss: Scalar value giving the loss
- grads: Dictionary with the same keys as self.params, mapping
parameter
names to gradients of the loss with respect to those parameters.
"""
scores = None
X = X.astype(self.dtype)
linear_cache = dict()
relu_cache = dict()
dropout_cache = dict()
out = X.copy()
"""
TODO: Implement the forward pass for the fully-connected neural
network, compute the scores and store them in the scores variable.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
if y is None: #mmmmmmmmodified
train = False
else:
train = True
scores = out
for i in range(1, self.num_layers):
linear_cache[str(i)] = scores
scores = linear_forward(X=scores,
W=self.params['W' + str(i)],
b=self.params['b' + str(i)])
relu_cache[str(i)] = scores
scores = relu_forward(scores)
if self.use_dropout:
if "seed" in self.dropout_params: #mmmmmmmmodified
scores, mask = dropout_forward(
scores,
p=self.dropout_params["p"],
train=train,
seed=self.dropout_params["seed"])
else:
scores, mask = dropout_forward(scores,
p=self.dropout_params["p"],
train=train)
dropout_cache[str(i)] = mask
linear_cache[str(self.num_layers)] = scores
scores = linear_forward(X=scores,
W=self.params['W' + str(self.num_layers)],
b=self.params['b' + str(self.num_layers)])
#######################################################################
# END OF YOUR CODE #
#######################################################################
# If y is None then we are in test mode so just return scores
if y is None:
return scores
loss, grads = 0, dict()
"""
TODO: Implement the backward pass for the fully-connected net. Store
the loss in the loss variable and all gradients in the grads
dictionary. Compute the loss with softmax. grads[k] has the gradients
for self.params[k]. Add L2 regularisation to the loss function.
NOTE: To ensure that your implementation matches ours and you pass the
automated tests, make sure that your L2 regularization includes a
factor of 0.5 to simplify the expression for the gradient.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
loss, dscore = softmax(scores, y)
regularization = 0
#add regularization to loss
for i in range(1, self.num_layers + 1):
regularization += np.sum(self.params['W' + str(i)]**2)
loss += 0.5 * self.reg * regularization
#backward through last w and b
dhidden_layer,grads['W' + str(self.num_layers)],grads['b' + str(self.num_layers)] = \
linear_backward(dscore, linear_cache[str(self.num_layers)], self.params['W' + str(self.num_layers)], self.params['b' + str(self.num_layers)])
#add regularization to W
grads['W' + str(self.num_layers)] += self.reg * self.params[
'W' + str(self.num_layers)]
#backward from all other layers
for i in range(self.num_layers - 1, 0, -1):
if self.use_dropout:
dhidden_layer = dropout_backward(dhidden_layer,
dropout_cache[str(i)],
self.dropout_params["p"],
self.dropout_params["train"])
dhidden_layer = relu_backward(dhidden_layer, relu_cache[str(i)])
dhidden_layer, grads['W' + str(i)],grads['b' + str(i)] = \
linear_backward(dhidden_layer, linear_cache[str(i)], self.params['W' + str(i)], self.params['b' + str(i)])
grads['W' + str(i)] += self.reg * self.params['W' + str(i)]
#######################################################################
# END OF YOUR CODE #
#######################################################################
return loss, grads
def loss(self, X, y=None):
"""
Compute loss and gradient for a minibatch of data.
Args:
- X: Input data, numpy array of shape (N, d_1, ..., d_k)
- y: Array of labels, of shape (N,). y[i] gives the label for X[i].
Returns:
If y is None, then run a test-time forward pass of the model and
return:
- scores: Array of shape (N, C) giving classification scores, where
scores[i, c] is the classification score for X[i] and class c.
If y is not None, then run a training-time forward and backward pass
and return a tuple of:
- loss: Scalar value giving the loss
- grads: Dictionary with the same keys as self.params, mapping
parameter
names to gradients of the loss with respect to those parameters.
"""
scores = None
X = X.astype(self.dtype)
linear_cache = dict()
relu_cache = dict()
dropout_cache = dict()
"""
TODO: Implement the forward pass for the fully-connected neural
network, compute the scores and store them in the scores variable.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
linear_cache[0] = relu_cache[0] = dropout_cache[0] = X
for i in range(1, self.num_layers + 1):
curr_id = str(i)
W_id = 'W' + curr_id
b_id = 'b' + curr_id
# if current layer is not the output layer
if i < self.num_layers:
# linear regression
if not self.use_dropout:
prev_layer_output = relu_cache[i - 1]
else:
prev_layer_output = dropout_cache[i - 1]
linear_cache[i] = linear_forward(prev_layer_output,
self.params[W_id],
self.params[b_id])
# relu activation
relu_cache[i] = relu_forward(linear_cache[i])
# dropout regularization
if self.use_dropout:
dropout_cache[i] = dropout_forward(
relu_cache[i], self.dropout_params['p'],
self.params[W_id], self.params[b_id])
# if current layer is the output layer
else:
# output layer outputs the estimate result of nn, scores
if not self.use_dropout:
prev_layer_output = relu_cache[i - 1]
else:
prev_layer_output = dropout_cache[i - 1]
scores = linear_forward(prev_layer_output, self.params[W_id],
self.params[b_id])
#######################################################################
# END OF YOUR CODE #
#######################################################################
# If y is None then we are in test mode so just return scores
if y is None:
return scores
loss, grads = 0, dict()
"""
TODO: Implement the backward pass for the fully-connected net. Store
the loss in the loss variable and all gradients in the grads
dictionary. Compute the loss with softmax. grads[k] has the gradients
for self.params[k]. Add L2 regularisation to the loss function.
NOTE: To ensure that your implementation matches ours and you pass the
automated tests, make sure that your L2 regularization includes a
factor of 0.5 to simplify the expression for the gradient.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
# use softmax to produce intermediate results, loss and dlogits
loss, dlogits = softmax(scores, y)
# iterate backward, output layer to input layer via hidden layers
for i in range(self.num_layers, 0, -1):
# set variable names
curr_id = str(i)
W_id = 'W' + curr_id
b_id = 'b' + curr_id
# L2 regularization
loss += 0.5 * self.reg * np.sum(self.params[W_id]**2)
# retrieve the result of upper layer from cache, prev_layer_output
prev_layer_output = relu_cache[
i - 1] if not self.use_dropout else dropout_cache[i - 1][0]
# if current layer is the output layer
if i == self.num_layers:
# perform linear bacward regression to update grads for W and b
dX, grads[W_id], grads[b_id] = linear_backward(
dlogits, prev_layer_output, self.params[W_id],
self.params[b_id])
# if current layer is not the output layer
else:
# dropout
if self.use_dropout:
mask = dropout_cache[i][1]
p, train = self.dropout_params['p'], self.dropout_params[
'train']
dX = dropout_backward(relu_cache[i], mask, p, train)
# relu
dX = relu_backward(dX, linear_cache[i])
# linear
dX, grads[W_id], grads[b_id] = linear_backward(
dX, prev_layer_output, self.params[W_id],
self.params[b_id])
#
grads[W_id] += self.reg * self.params[W_id]
#######################################################################
# END OF YOUR CODE #
#######################################################################
return loss, grads
def loss(self, X, y=None):
"""
Compute loss and gradient for a minibatch of data.
Args:
- X: Input data, numpy array of shape (N, d_1, ..., d_k)
- y: Array of labels, of shape (N,). y[i] gives the label for X[i].
Returns:
If y is None, then run a test-time forward pass of the model and
return:
- scores: Array of shape (N, C) giving classification scores, where
scores[i, c] is the classification score for X[i] and class c.
If y is not None, then run a training-time forward and backward pass
and return a tuple of:
- loss: Scalar value giving the loss
- grads: Dictionary with the same keys as self.params, mapping
parameter
names to gradients of the loss with respect to those parameters.
"""
scores = None
X = X.astype(self.dtype)
linear_cache = dict()
relu_cache = dict()
dropout_cache = dict()
"""
TODO: Implement the forward pass for the fully-connected neural
network, compute the scores and store them in the scores variable.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
train = True if y is not None else False
if self.use_dropout:
p = self.dropout_params["p"]
seed = self.dropout_params["seed"]
for layer in range(1, self.num_layers + 1):
W = self.params["W" + str(layer)]
b = self.params["b" + str(layer)]
input = X if layer == 1 else (
dropout_cache[layer -
1][0] if self.use_dropout else relu_cache[layer -
1])
if layer != self.num_layers:
linear_cache[layer] = linear_forward(input, W, b)
relu_cache[layer] = relu_forward(linear_cache[layer])
if self.use_dropout:
dropout_cache[layer] = dropout_forward(
relu_cache[layer], p, train, seed)
else:
scores = linear_forward(input, W, b)
#######################################################################
# END OF YOUR CODE #
#######################################################################
# If y is None then we are in test mode so just return scores
if not train:
return scores
loss, grads = 0, dict()
"""
TODO: Implement the backward pass for the fully-connected net. Store
the loss in the loss variable and all gradients in the grads
dictionary. Compute the loss with softmax. grads[k] has the gradients
for self.params[k]. Add L2 regularisation to the loss function.
NOTE: To ensure that your implementation matches ours and you pass the
automated tests, make sure that your L2 regularization includes a
factor of 0.5 to simplify the expression for the gradient.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
loss, dscores = softmax(scores, y)
loss += self.l2regular()
for layer in reversed(range(1, self.num_layers + 1)):
w_key = "W" + str(layer)
b_key = "b" + str(layer)
W = self.params[w_key]
b = self.params[b_key]
if layer == self.num_layers:
input_linear = dropout_cache[
layer - 1][0] if self.use_dropout else relu_cache[layer -
1]
dX, dW, db = linear_backward(dscores, input_linear, W, b)
dW += self.reg * W
else:
if self.use_dropout:
input_drop = relu_cache[layer]
mask = dropout_cache[layer][1]
dX = dropout_backward(dX, mask, p, train)
input_relu = linear_cache[layer]
dX = relu_backward(dX, input_relu)
if layer == 1:
input_linear = X
else:
input_linear = dropout_cache[
layer -
1][0] if self.use_dropout else relu_cache[layer - 1]
dout = dX
dX, dW, db = linear_backward(dout, input_linear, W, b)
dW += self.reg * W
grads[w_key] = dW
grads[b_key] = db
#######################################################################
# END OF YOUR CODE #
#######################################################################
return loss, grads
def loss(self, X, y=None):
"""
Compute loss and gradient for a minibatch of data.
Args:
- X: Input data, numpy array of shape (N, d_1, ..., d_k)
- y: Array of labels, of shape (N,). y[i] gives the label for X[i].
Returns:
If y is None, then run a test-time forward pass of the model and
return:
- scores: Array of shape (N, C) giving classification scores, where
scores[i, c] is the classification score for X[i] and class c.
If y is not None, then run a training-time forward and backward pass
and return a tuple of:
- loss: Scalar value giving the loss
- grads: Dictionary with the same keys as self.params, mapping
parameter
names to gradients of the loss with respect to those parameters.
"""
scores = None
X = X.astype(self.dtype)
linear_cache = dict()
relu_cache = dict()
dropout_cache = dict()
"""
TODO: Implement the forward pass for the fully-connected neural
network, compute the scores and store them in the scores variable.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
# Forward pass: loop through all layers
# store the linear activations, relu and masks
for i in range(1, self.num_layers):
if i == 1:
linear_cache["L{}".format(i)] = linear_forward(
X, self.params["W{}".format(i)],
self.params["b{}".format(i)])
else:
if self.use_dropout:
linear_cache["L{}".format(i)] = linear_forward(
dropout_cache["D{}".format(i - 1)],
self.params["W{}".format(i)],
self.params["b{}".format(i)])
else:
linear_cache["L{}".format(i)] = linear_forward(
relu_cache["R{}".format(i - 1)],
self.params["W{}".format(i)],
self.params["b{}".format(i)])
relu_cache["R{}".format(i)] = relu_forward(
linear_cache["L{}".format(i)])
if self.use_dropout:
s = None
if 'seed' in self.dropout_params.keys():
s = self.dropout_params['seed']
p = self.dropout_params["p"]
t = self.dropout_params["train"]
dropout_cache["D{}".format(i)], dropout_cache["M{}".format(
i)] = dropout_forward(relu_cache["R{}".format(i)],
p=p,
train=t,
seed=s)
#Linear final layer
scores = None
if self.use_dropout:
scores = linear_forward(
dropout_cache["D{}".format(self.num_layers - 1)],
self.params["W{}".format(self.num_layers)],
self.params["b{}".format(self.num_layers)])
else:
scores = linear_forward(
relu_cache["R{}".format(self.num_layers - 1)],
self.params["W{}".format(self.num_layers)],
self.params["b{}".format(self.num_layers)])
#######################################################################
# END OF YOUR CODE #
#######################################################################
# If y is None then we are in test mode so just return scores
if y is None:
return scores
loss, grads = 0, dict()
"""
TODO: Implement the backward pass for the fully-connected net. Store
the loss in the loss variable and all gradients in the grads
dictionary. Compute the loss with softmax. grads[k] has the gradients
for self.params[k]. Add L2 regularisation to the loss function.
NOTE: To ensure that your implementation matches ours and you pass the
automated tests, make sure that your L2 regularization includes a
factor of 0.5 to simplify the expression for the gradient.
"""
#######################################################################
# BEGIN OF YOUR CODE #
#######################################################################
# Compute the loss and gradients using softmax
loss, dx = softmax(scores, y)
# Apply L2 Regularisation
for i in range(1, self.num_layers + 1):
loss += (0.5 * self.reg) * np.sum(
np.square(self.params["W{}".format(i)]))
# Backwards pass: Final linear layer
if self.use_dropout:
dx, dW, db = linear_backward(
dx, dropout_cache["D{}".format(self.num_layers - 1)],
self.params["W{}".format(self.num_layers)],
self.params["b{}".format(self.num_layers)])
else:
dx, dW, db = linear_backward(
dx, relu_cache["R{}".format(self.num_layers - 1)],
self.params["W{}".format(self.num_layers)],
self.params["b{}".format(self.num_layers)])
grads["W{}".format(self.num_layers)] = dW
# L2 Regularisation
grads["W{}".format(
self.num_layers)] += self.reg * self.params["W{}".format(
self.num_layers)]
grads["b{}".format(self.num_layers)] = db
# Loop backwards through the layers to the first layer
for j in reversed(range(1, self.num_layers)):
# Reverse dropout
if self.use_dropout:
dx = dropout_backward(dx,
mask=dropout_cache["M{}".format(j)],
p=self.dropout_params["p"],
train=self.dropout_params["train"])
# Relu backward pass with incoming Z value
dx = relu_backward(dx, linear_cache["L{}".format(j)])
# Linear pass with activation value of incoming layer
if j == 1:
dx, dW, db = linear_backward(dx, X,
self.params["W{}".format(j)],
self.params["b{}".format(j)])
else:
foo = None
if self.use_dropout:
dx, dW, db = linear_backward(
dx, dropout_cache["D{}".format(j - 1)],
self.params["W{}".format(j)],
self.params["b{}".format(j)])
else:
dx, dW, db = linear_backward(
dx, relu_cache["R{}".format(j - 1)],
self.params["W{}".format(j)],
self.params["b{}".format(j)])
grads["W{}".format(j)] = dW
# Regularisation
grads["W{}".format(j)] += self.reg * self.params["W{}".format(j)]
grads["b{}".format(j)] = db
#######################################################################
# END OF YOUR CODE #
#######################################################################
return loss, grads