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hyperparam_two_loop_bfgs_bfgs.py
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hyperparam_two_loop_bfgs_bfgs.py
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from __future__ import absolute_import
from __future__ import print_function
import autograd.numpy as np
import autograd.numpy.random as npr
from autograd.scipy.misc import logsumexp
from autograd import grad
from scipy import optimize
import sys
import matplotlib.pyplot as plt
filename = "default.txt" if len(sys.argv) < 2 else sys.argv[1]
def logsumexp(X, axis=1):
max_X = np.max(X)
return max_X + np.log(np.sum(np.exp(X - max_X), axis=axis, keepdims=True))
def get_wine_data():
print("Loading training data...")
wine_data_file = open('./wines_data/wine.data', 'r')
num_class_1, num_class_2, num_class_3 = 59, 71, 48
wines_data = []
for line in wine_data_file:
entries = line.split(',')
wine_type = int(entries[0]) # 1, 2, or 3
wine_type_one_hot = [1., 0., 0.] if wine_type == 1 else [0., 1., 0.] if wine_type == 2 else [0., 0., 1.]
wine_features = map(float, entries[1:-1])
wine_data = wine_features
wine_data.extend(wine_type_one_hot)
wines_data.append(wine_data)
wines_data = np.array(wines_data)
np.random.shuffle(wines_data)
features, labels = wines_data[:, :-3], wines_data[:, -3:]
num_data_pts = len(wines_data)
train_set_size = 0.8 * num_data_pts
train_data, train_labels = features[:train_set_size], labels[:train_set_size]
test_data, test_labels = features[train_set_size:], labels[train_set_size:]
assert np.sum(wines_data[:, -3]) == num_class_1
assert np.sum(wines_data[:, -2]) == num_class_2
assert np.sum(wines_data[:, -1]) == num_class_3
return num_data_pts, train_data, train_labels, test_data, test_labels
def sigmoid(x):
return np.exp(-np.logaddexp(0, -x)) if x >= 0 else np.exp(x - np.logaddexp(x, 0))
def make_nn_funs(layer_sizes, L2_reg):
shapes = zip(layer_sizes[:-1], layer_sizes[1:])
N = sum((m+1)*n for m, n in shapes)
def unpack_layers(W_vect):
for m, n in shapes:
yield W_vect[:m*n].reshape((m,n)), W_vect[m*n:m*n+n]
W_vect = W_vect[(m+1)*n:]
def predictions(W_vect, inputs, alpha):
outputs = 0
for W, b in unpack_layers(W_vect):
prev_outputs = outputs
outputs = np.dot(np.array(inputs), W) + b
inputs = np.tanh(outputs)
return sigmoid(alpha) * outputs + (1 - sigmoid(alpha)) * prev_outputs
def loss(params, X, T):
W_vect = params[:-1]
alpha = params[-1]
log_prior = -L2_reg * np.dot(W_vect, W_vect)
preds = predictions(W_vect, X, alpha)
normalised_log_probs = preds - logsumexp(preds)
log_lik = np.sum(normalised_log_probs * T)
return -1.0 * (log_prior + log_lik)
def frac_err(params, X, T):
W_vect = params[:-1]
alpha = params[-1]
percent_wrong = np.mean(np.argmax(T, axis=1) != np.argmax(predictions(W_vect, X, alpha), axis=1))
return percent_wrong
return N, predictions, loss, frac_err
def make_batches(N_data, batch_size):
return [slice(i, min(i+batch_size, N_data))
for i in range(0, N_data, batch_size)]
def run_nn(N, input_size, output_size):
integer_part = int(np.floor(N[0]))
alpha = N[0] - integer_part
# Network parameters
layer_sizes = [input_size]
layer_sizes.extend([output_size for i in range(0, integer_part - 1)])
L2_reg = 1.0
# Training parameters
param_scale = 0.1
# Load and process wines data
N_data, train_images, train_labels, test_images, test_labels = get_wine_data()
batch_size = len(train_images)
# Make neural net functions
N_weights, pred_fun, loss_fun, frac_err = make_nn_funs(layer_sizes, L2_reg)
# Gradient with respect to weights and alpha
loss_grad_P = grad(loss_fun, 0)
# Initialize weights
rs = npr.RandomState(11)
W = rs.randn(N_weights) * param_scale
print(" Train err | Test err | Alpha")
f_out = open(filename, 'w')
f_out.write(" Train err | Test err | Alpha\n")
f_out.close()
def print_perf(params):
f_out = open(filename, 'a')
test_perf = frac_err(params, test_images, test_labels)
train_perf = frac_err(params, train_images, train_labels)
print("{0:15}|{1:15}|{2:15}".format(train_perf, test_perf, params[-1]))
f_out.write("{0:15}|{1:15}|{2:15}\n".format(train_perf, test_perf, params[-1]))
f_out.close()
# Minimize with BFGS
res = optimize.minimize(loss_fun, np.append(W, alpha), jac=loss_grad_P, method='L-BFGS-B', \
args=(train_images, train_labels), options={'disp': True, 'maxiter': 2})
print(res)
final_test_err = frac_err(res.x, train_images, train_labels)
print(N[0], final_test_err)
return final_test_err
if __name__ == '__main__':
# Gradient of inner loop with respect to N
run_nn_grad = grad(run_nn, 0)
N = 3.4
optimize.minimize(run_nn, N, jac=run_nn_grad, method='L-BFGS-B', \
args=(12, 3), options={'disp': True})