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"""
Benchmark for SGD regression
Compares SGD regression against coordinate descent and Ridge
on synthetik data.
"""
print __doc__
# Author: Peter Prettenhofer <peter.prettenhofer@gmail.com>
# License: BSD Style.
import numpy as np
import pylab as pl
import gc
from time import time
from sklearn.linear_model import Ridge, SGDRegressor, ElasticNet
from sklearn.metrics import mean_squared_error
from sklearn.datasets.samples_generator import make_regression
if __name__ == "__main__":
list_n_samples = np.linspace(100, 10000, 5).astype(np.int)
list_n_features = [10, 100, 1000]
n_test = 1000
noise = 0.1
alpha = 0.01
sgd_results = np.zeros((len(list_n_samples), len(list_n_features), 2))
elnet_results = np.zeros((len(list_n_samples), len(list_n_features), 2))
ridge_results = np.zeros((len(list_n_samples), len(list_n_features), 2))
for i, n_train in enumerate(list_n_samples):
for j, n_features in enumerate(list_n_features):
X, y, coef = make_regression(
n_samples=n_train + n_test, n_features=n_features,
noise=noise, coef=True)
X_train = X[:n_train]
y_train = y[:n_train]
X_test = X[n_train:]
y_test = y[n_train:]
print "======================="
print "Round %d %d" % (i, j)
print "n_features:", n_features
print "n_samples:", n_train
# Shuffle data
idx = np.arange(n_train)
np.random.seed(13)
np.random.shuffle(idx)
X_train = X_train[idx]
y_train = y_train[idx]
std = X_train.std(axis=0)
mean = X_train.mean(axis=0)
X_train = (X_train - mean) / std
X_test = (X_test - mean) / std
std = y_train.std(axis=0)
mean = y_train.mean(axis=0)
y_train = (y_train - mean) / std
y_test = (y_test - mean) / std
gc.collect()
print "- benching ElasticNet"
clf = ElasticNet(alpha=alpha, rho=0.5, fit_intercept=False)
tstart = time()
clf.fit(X_train, y_train)
elnet_results[i, j, 0] = mean_squared_error(clf.predict(X_test),
y_test)
elnet_results[i, j, 1] = time() - tstart
gc.collect()
print "- benching SGD"
n_iter = np.ceil(10 ** 4.0 / n_train)
clf = SGDRegressor(alpha=alpha, fit_intercept=False,
n_iter=n_iter, learning_rate="invscaling",
eta0=.01, power_t=0.25)
tstart = time()
clf.fit(X_train, y_train)
sgd_results[i, j, 0] = mean_squared_error(clf.predict(X_test),
y_test)
sgd_results[i, j, 1] = time() - tstart
gc.collect()
print "- benching RidgeRegression"
clf = Ridge(alpha=alpha, fit_intercept=False)
tstart = time()
clf.fit(X_train, y_train)
ridge_results[i, j, 0] = mean_squared_error(clf.predict(X_test),
y_test)
ridge_results[i, j, 1] = time() - tstart
# Plot results
i = 0
m = len(list_n_features)
pl.figure(figsize=(5 * 2, 4 * m))
for j in range(m):
pl.subplot(m, 2, i + 1)
pl.plot(list_n_samples, np.sqrt(elnet_results[:, j, 0]),
label="ElasticNet")
pl.plot(list_n_samples, np.sqrt(sgd_results[:, j, 0]),
label="SGDRegressor")
pl.plot(list_n_samples, np.sqrt(ridge_results[:, j, 0]),
label="Ridge")
pl.legend(prop={"size": 10})
pl.xlabel("n_train")
pl.ylabel("RMSE")
pl.title("Test error - %d features" % list_n_features[j])
i += 1
pl.subplot(m, 2, i + 1)
pl.plot(list_n_samples, np.sqrt(elnet_results[:, j, 1]),
label="ElasticNet")
pl.plot(list_n_samples, np.sqrt(sgd_results[:, j, 1]),
label="SGDRegressor")
pl.plot(list_n_samples, np.sqrt(ridge_results[:, j, 1]),
label="Ridge")
pl.legend(prop={"size": 10})
pl.xlabel("n_train")
pl.ylabel("Time [sec]")
pl.title("Training time - %d features" % list_n_features[j])
i += 1
pl.subplots_adjust(hspace=.30)
pl.show()
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