hidden_layer_sizes = [hidden_layer_sizes]
hidden_layer_sizes = list(hidden_layer_sizes)
layer_units = ([n_features] + hidden_layer_sizes + [mlp.n_outputs_])
activations = [X]
activations.extend(np.empty((batch_size, n_fan_out))
for n_fan_out in layer_units[1:])
deltas = [np.empty_like(a_layer) for a_layer in activations]
coef_grads = [np.empty((n_fan_in_, n_fan_out_))
for n_fan_in_, n_fan_out_ in zip(layer_units[:-1],
layer_units[1:])]
intercept_grads = [np.empty(n_fan_out_) for n_fan_out_ in layer_units[1:]]
# ==========================================================================
print(mlp.out_activation_)
activations = mlp._forward_pass(activations)
loss, coef_grads, intercept_grads = mlp._backprop(
X, target, activations, deltas, coef_grads, intercept_grads)
nn = NeuralNetwork( X_data = X,
Y_data = target,
n_hidden_neurons = 3,
n_categories = 1,
activation_func_out = 'identity',
activation_func = 'relu',
cost_func = 'MSE')
# Copy the weights and biases from the scikit-learn network to your own.
nn.hidden_weights, nn.output_weights = mlp.coefs_
nn.hidden_bias, nn.output_bias = mlp.intercepts_
def test_neuralNetwork_backpropagation_multiple_outputs():
# Similar to the test_neuralNetwork_backpropagation() test, but with
# multiple samples and features, X having dimensions
# (n_samples, n_features) = (3,2), as well as the target having dimensions
# (n_outputs) = (2)
from sklearn.neural_network import MLPRegressor
X = np.array([[0, 1], [1, 2], [2, 3]])
y = np.array([[0, 1], [2, 3], [3, 4]])
mlp = MLPRegressor(solver='sgd',
alpha=0.0,
learning_rate='constant',
learning_rate_init=1e-20,
max_iter=1,
hidden_layer_sizes=(3, 3),
random_state=1,
activation='logistic')
# Force sklearn to set up all the matrices by fitting a data set.
with warnings.catch_warnings():
warnings.simplefilter("ignore")
mlp.fit(X, y)
W_skl = mlp.coefs_
b_skl = mlp.intercepts_
nn = NeuralNetwork(inputs=2,
outputs=2,
layers=3,
neurons=3,
activations='sigmoid',
silent=True)
nn.addLayer()
nn.addLayer()
nn.addOutputLayer(activations='identity')
for i, w in enumerate(W_skl):
nn.weights[i] = w
for i, b in enumerate(b_skl):
nn.biases[i] = np.expand_dims(b, axis=1)
# ========================================================================
n_samples, n_features = X.shape
batch_size = n_samples
hidden_layer_sizes = mlp.hidden_layer_sizes
if not hasattr(hidden_layer_sizes, "__iter__"):
hidden_layer_sizes = [hidden_layer_sizes]
hidden_layer_sizes = list(hidden_layer_sizes)
layer_units = ([n_features] + hidden_layer_sizes + [mlp.n_outputs_])
activations = [X]
activations.extend(
np.empty((batch_size, n_fan_out)) for n_fan_out in layer_units[1:])
deltas = [np.empty_like(a_layer) for a_layer in activations]
coef_grads = [
np.empty((n_fan_in_, n_fan_out_))
for n_fan_in_, n_fan_out_ in zip(layer_units[:-1], layer_units[1:])
]
intercept_grads = [np.empty(n_fan_out_) for n_fan_out_ in layer_units[1:]]
# ========================================================================
activations = mlp._forward_pass(activations)
if y.ndim == 1:
y = y.reshape((-1, 1))
loss, coef_grads, intercept_grads = mlp._backprop(X, y, activations,
deltas, coef_grads,
intercept_grads)
yhat = nn.forward_pass(X.T)
nn.backpropagation(yhat.T, y)
for i, d_bias in enumerate(nn.d_biases):
assert np.squeeze(d_bias) == pytest.approx(
np.squeeze(intercept_grads[i]))
for i, d_weight in enumerate(nn.d_weights):
assert np.squeeze(d_weight) == pytest.approx(np.squeeze(coef_grads[i]))
# lbfgs does not support mini-batches
if mlp_estimator.solver == 'lbfgs':
batch_size = n_samples
elif mlp_estimator.batch_size == 'auto':
batch_size = min(200, n_samples)
else:
if mlp_estimator.batch_size < 1 or mlp_estimator.batch_size > n_samples:
warnings.warn("Got `batch_size` less than 1 or larger than "
"sample size. It is going to be clipped")
batch_size = np.clip(mlp_estimator.batch_size, 1, n_samples)
# Initialize lists
activations = [X]
activations.extend(
np.empty((batch_size, n_fan_out)) for n_fan_out in layer_units[1:])
deltas = [np.empty_like(a_layer) for a_layer in activations]
coef_grads = [
np.empty((n_fan_in_, n_fan_out_))
for n_fan_in_, n_fan_out_ in zip(layer_units[:-1], layer_units[1:])
]
intercept_grads = [np.empty(n_fan_out_) for n_fan_out_ in layer_units[1:]]
activations = mlp_estimator._forward_pass(activations)
print('output: ', activations[mlp_estimator.n_layers_ - 1])
for i in range(mlp_estimator.n_layers_ - 1):
print('weight[%d]: ' % i, mlp_estimator.coefs_[i])
print('bias[%d]: ' % i, mlp_estimator.intercepts_[i])
def test_neuralNetwork_backpropagation():
# We re-use the test_neuralNetwork_network networks and this time check
# that the computed backpropagation derivatives are equal.
from sklearn.neural_network import MLPRegressor
X = [[0.0], [1.0], [2.0], [3.0], [4.0], [5.0]]
y = [0, 2, 4, 6, 8, 10]
mlp = MLPRegressor(solver='sgd',
alpha=0.0,
hidden_layer_sizes=(3, 3),
random_state=1,
activation='logistic')
# Force sklearn to set up all the matrices by fitting a data set.
with warnings.catch_warnings():
warnings.simplefilter("ignore")
mlp.fit(X, y)
# Throw away all the fitted values, randomize W and b matrices.
np.random.seed(18)
for i, coeff in enumerate(mlp.coefs_):
mlp.coefs_[i] = np.random.normal(size=coeff.shape)
for i, bias in enumerate(mlp.intercepts_):
mlp.intercepts_[i] = np.random.normal(size=bias.shape)
W_skl = mlp.coefs_
b_skl = mlp.intercepts_
nn = NeuralNetwork(inputs=1,
outputs=1,
layers=3,
neurons=3,
activations='sigmoid',
silent=False)
nn.addLayer()
nn.addLayer()
nn.addOutputLayer(activations='identity')
nn.weights = W_skl
for i, b in enumerate(b_skl):
nn.biases[i] = np.expand_dims(b, axis=1)
# From the sklearn source, we need to set up some lists to use the _backprop
# function in MLPRegressor, see:
#
# https://github.com/scikit-learn/scikit-learn/blob/bac89c2/sklearn/neural_network/multilayer_perceptron.py#L355
#
# ========================================================================
# Initialize lists
X = np.array([[1.125982598]])
y = np.array([8.29289285])
mlp.predict(X)
n_samples, n_features = X.shape
batch_size = n_samples
hidden_layer_sizes = mlp.hidden_layer_sizes
# Make sure self.hidden_layer_sizes is a list
if not hasattr(hidden_layer_sizes, "__iter__"):
hidden_layer_sizes = [hidden_layer_sizes]
hidden_layer_sizes = list(hidden_layer_sizes)
layer_units = ([n_features] + hidden_layer_sizes + [mlp.n_outputs_])
activations = [X]
activations.extend(
np.empty((batch_size, n_fan_out)) for n_fan_out in layer_units[1:])
deltas = [np.empty_like(a_layer) for a_layer in activations]
coef_grads = [
np.empty((n_fan_in_, n_fan_out_))
for n_fan_in_, n_fan_out_ in zip(layer_units[:-1], layer_units[1:])
]
intercept_grads = [np.empty(n_fan_out_) for n_fan_out_ in layer_units[1:]]
# ========================================================================
activations = mlp._forward_pass(activations)
loss, coef_grads, intercept_grads = mlp._backprop(X, y, activations,
deltas, coef_grads,
intercept_grads)
yhat = nn(X)
nn.backpropagation(yhat, y)
for i, d_bias in enumerate(nn.d_biases):
assert np.squeeze(d_bias) == pytest.approx(
np.squeeze(intercept_grads[i]))
for i, d_weight in enumerate(nn.d_weights):
assert np.squeeze(d_weight) == pytest.approx(np.squeeze(coef_grads[i]))
def test_regressor(X_train,
y_train,
X_test,
y_test,
nn_layers,
sk_hidden_layers,
input_activation,
output_activation,
alpha=0.0):
if input_activation == "sigmoid":
sk_input_activation = "logistic"
else:
sk_input_activation = input_activation
if output_activation == "sigmoid":
sk_output_activation = "logistic"
else:
sk_output_activation = output_activation
mlp = MLPRegressor(
solver='sgd', # Stochastic gradient descent.
activation=sk_input_activation, # Skl name for sigmoid.
alpha=alpha, # No regularization for simplicity.
hidden_layer_sizes=sk_hidden_layers) # Full NN size is (1,3,3,1).
mlp.out_activation_ = sk_output_activation
# Force sklearn to set up all the necessary matrices by fitting a data
# set. We dont care if it converges or not, so lets ignore raised
# warnings.
with warnings.catch_warnings():
warnings.simplefilter("ignore")
mlp.fit(X_train, y_train)
# =====================================================================
n_samples, n_features = X_train.shape
batch_size = n_samples
hidden_layer_sizes = mlp.hidden_layer_sizes
if not hasattr(hidden_layer_sizes, "__iter__"):
hidden_layer_sizes = [hidden_layer_sizes]
hidden_layer_sizes = list(hidden_layer_sizes)
layer_units = ([n_features] + hidden_layer_sizes + [mlp.n_outputs_])
activations = [X_test]
activations.extend(
np.empty((batch_size, n_fan_out)) for n_fan_out in layer_units[1:])
deltas = [np.empty_like(a_layer) for a_layer in activations]
coef_grads = [
np.empty((n_fan_in_, n_fan_out_))
for n_fan_in_, n_fan_out_ in zip(layer_units[:-1], layer_units[1:])
]
intercept_grads = [
np.empty(n_fan_out_) for n_fan_out_ in layer_units[1:]
]
# =====================================================================
mlp.out_activation_ = sk_output_activation
activations = mlp._forward_pass(activations)
loss, coef_grads, intercept_grads = mlp._backprop(
X_test, y_test, activations, deltas, coef_grads, intercept_grads)
# Activates my own MLP
nn = MultilayerPerceptron(nn_layers,
activation=input_activation,
output_activation=output_activation,
alpha=alpha)
# Copy the weights and biases from the scikit-learn network to your
# own.
for i, w in enumerate(mlp.coefs_):
nn.weights[i] = cp.deepcopy(w.T)
for i, b in enumerate(mlp.intercepts_):
nn.biases[i] = cp.deepcopy(b.T.reshape(-1, 1))
# Call your own backpropagation function, and you're ready to compare
# with the scikit-learn code.
y_sklearn = mlp.predict(X_test)
y = nn.predict(cp.deepcopy(X_test).T)
# Asserts that the forward pass is correct
assert np.allclose(y, y_sklearn), ("Prediction {} != {}".format(
y, y_sklearn))
delta_w, delta_b = nn._back_propagate(X_test.T, y_test)
# Asserts that the the activations is correct in back propagation
for i, a in enumerate(nn.activations):
print(i, a.T, activations[i])
assert np.allclose(a.T,
activations[i]), "error in layer {}".format(i)
else:
print("Activations are correct.")
# Asserts that the the biases is correct in back propagation
for i, derivative_bias in enumerate(delta_b):
print(i, derivative_bias.T, intercept_grads[i])
assert np.allclose(
derivative_bias.T,
intercept_grads[i]), ("error in layer {}".format(i))
else:
print("Biases derivatives are correct.")
# Asserts that the the weights is correct in back propagation
for i, derivative_weight in enumerate(delta_w):
print(i, derivative_weight.T, coef_grads[i])
assert np.allclose(derivative_weight.T,
coef_grads[i]), "error in layer {}".format(i)
else:
print("Weight derivatives are correct.")
print("Test complete\n")
