def main():
if len(sys.argv) < 2:
print("Usage:\n\t{} [housing-data]".format(sys.argv[0]))
sys.exit(1)
dataset = reader.read(sys.argv[1], delim=' ')
# Exapand features with nonlinear functions
# Need to put them back together to handle
features, labels = util.fldivide(dataset)
features, scale = scaling.unit_scale(features)
features = util.basis_expand(features, lambda x: x ** 2, lambda x: x ** 3)
features = np.hstack([features, np.ones((len(features), 1))])
dataset = util.fljoin(features, labels)
reg = NormalEquationLinearRegressor(regularization=1e-8)
cv = CrossValidator(reg)
feat_indices, feat_errors = cv.best_3features_topN(dataset, n=5)
for indices, err in zip(feat_indices, feat_errors):
bestfeats = np.dstack([features[:, i] for i in indices]).squeeze()
data = util.fljoin(bestfeats, labels)
reg.train(data)
print(reg.w)
print("indices = {}, err = {}".format(indices, err))
def train(self, x):
x, y = util.fldivide(x)
# Check if any columns of x are all zeros (bad news for inversion)
try:
self.w = np.linalg.inv(x.T.dot(x) + self.l * np.eye(len(x[0]))).dot(x.T).dot(y)
except np.linalg.linalg.LinAlgError as e:
print(e)
self.w = np.empty(len(x[0]))
self.w[:] = np.NAN
def best_2features(self, dataset, k=10):
feats, labels = util.fldivide(dataset)
N = len(feats[0])
err = np.ones((N, N))
for i in range(len(feats[0])):
for j in range(i+1, len(feats[0])):
f1, f2, l = feats[:, i], feats[:, j], labels
d = np.dstack((f1, f2, l)).squeeze()
err[i, j] = self.kfold(d)
minpos = np.unravel_index(err.argmin(), err.shape)
return minpos[0], minpos[1], err[minpos[0], minpos[1]]
def train(self, x):
x, y = util.fldivide(x)
iters = 0
m, n = x.shape
self.w = np.empty(n)
new_w = np.ones_like(self.w)
while np.linalg.norm(self.w - new_w) > self.convergence:
np.copyto(self.w, new_w)
for j in range(n):
diff = sum((self.w.dot(x[i]) - y[i]) * x[i, j] for i in range(m))
new_w[j] = self.w[j] - (self.learn_rate / m) * (diff + self.l * self.w[j])
iters += 1
self.w = new_w
def main():
if len(sys.argv) < 2:
print("Usage:\n\t{} [trainfile] [testfile]".format(sys.argv[0]))
sys.exit(1)
train_file, test_file = sys.argv[1:]
train_data, train_labels = util.fldivide(read(train_file))
test_data, test_labels = util.fldivide(read(test_file))
for i in range(5):
nth_train_data = util.make_nth_order(train_data, i)
nth_train = np.hstack((nth_train_data, train_labels.reshape((len(train_labels), 1))))
nth_test_data = util.make_nth_order(test_data, i)
model = GradientDescentLinearRegressor(learn_rate=0.4, regularization=1e1)
model.train(nth_train)
predicted = model.predict(nth_test_data)
mse = model.error(predicted, test_labels)
plot_scatter_curve(test_data, test_labels, model.w, fignum=i,
title="Gradient Descent, order {}, alpha={}, lambda={}, mse={}".format(i, model.learn_rate, model.l, mse))
plt.show()
def kfold(self, dataset, k=10):
# Divide data into k-groups
kgroups = util.kdivide(dataset, k)
err = []
for i in range(len(kgroups)):
# Catenate testing samples (leave out group i)
train_set = np.vstack(kgroups[:i] + kgroups[i+1:])
test_set = kgroups[i]
# Run classifier, test with test set
self.clf.train(train_set)
test_f, test_l = util.fldivide(test_set)
predicted_l = self.clf.predict(test_f)
err.append(self.clf.error(predicted_l, test_l))
# Return mean error from all k-groups
return sum(err) / len(err)
def best_3features_topN(self, dataset, n=1, k=10):
feats, labels = util.fldivide(dataset)
N = len(feats[0])
err = np.empty((N, N, N))
err[:] = np.NAN
for i in range(len(feats[0])):
for j in range(i+1, len(feats[0])):
for k in range(j+1, len(feats[0])):
f1, f2, f3, l = feats[:, i], feats[:, j], feats[:, k], labels
d = np.dstack((f1, f2, f3, l)).squeeze()
err[i, j, k] = self.kfold(d)
# Return indices of top N sets of three features + their error
indices = []
errors = []
for i in range(n):
minpos = np.unravel_index(np.nanargmin(err), err.shape)
indices.append(minpos)
errors.append(err[minpos])
err[minpos] = np.NAN
return indices, errors