bench_lasso_screening.py

import time
import numpy as np
from scipy import linalg, io, sparse
import matplotlib.pyplot as plt

from sklearn.externals.joblib import Memory
from sklearn.linear_model import lasso_path
from sklearn.datasets.mldata import fetch_mldata
from sklearn import datasets

screening_methods = {
    0: "No screening",
    1: "GAP SAFE (sphere)",
}

markers = ['s', 'd', '^', 'v', '<', 'p', '>']
colors = plt.rcParams['axes.color_cycle']

plt.close('all')

import sys
dataset_id = 0

if len(sys.argv) > 1:
    dataset_id = int(sys.argv[1])

eps = 1e-2  # the smaller it is the longer is the path

if dataset_id == 0:
    dataset_name = 'leukemia'
    data = fetch_mldata(dataset_name)
    X = data.data
    y = data.target
    X = X.astype(float)
    y = y.astype(float)
    y /= linalg.norm(y)
elif dataset_id == 1:
    dataset_name = 'news'

    def get_Xy_news():
        data = datasets.fetch_20newsgroups(categories=['comp.graphics',
                                                       'talk.religion.misc'])
        from sklearn.feature_extraction.text import TfidfVectorizer
        vect = TfidfVectorizer(max_df=0.95, min_df=2, stop_words='english')
        X = vect.fit_transform(data.data)
        y = data.target.astype(np.float)
        y[y == 0] = -1.
        return X, y

    mem = Memory('.')
    X, y, = mem.cache(get_Xy_news)()

elif dataset_id == 2:
    dataset_name = 'rcv1'

    data = io.loadmat('rcv1_train.binary.mat')
    X = data['X'].astype(np.float)
    y = data['y'].astype(np.float).ravel()
    eps = 1e-2  # the smaller it is the longer is the path

if sparse.issparse(X):
    pass
else:
    # Standardize data (easier to set the l1_ratio parameter)
    X /= np.sqrt(np.sum(X ** 2, axis=0))
    mask = np.sum(np.isnan(X), axis=0) == 0
    if np.any(mask):
        X = X[:, mask]

print(X.shape)

y /= linalg.norm(y)  # to correct for tol scaling

# Compute paths

tols = range(2, 11, 2)
screenings = [0, 10]

times = np.zeros((len(screenings), len(tols)))

plt.close('all')

for itol, tol in enumerate(tols):
    plt.figure()
    for iscreening, screening in enumerate(screenings):
        begin = time.time()
        print("Computing regularization path using the lasso "
              "with screening=%d..." % screening)
        alphas, coefs, gaps = lasso_path(X, y, eps, n_alphas=100,
                                         precompute=False, tol=10 ** (-tol),
                                         verbose=0, max_iter=3000,
                                         screening=screening)

        duration = time.time() - begin
        print(duration)

        times[iscreening, itol] = duration

        # Display results
        gap_lasso = np.maximum(np.abs(gaps), 1e-15)

        l1 = plt.plot(-np.log10(alphas / np.max(alphas)), np.log10(gaps.T),
                      label=screening_methods[iscreening],
                      marker=markers[iscreening])
        plt.axhline(-tol, linestyle='--', color='k')

    plt.xlabel('-Log(alpha)')
    plt.ylabel('Log(gap)')
    plt.axis('tight')
    plt.legend(loc="lower right")
    plt.show()
    time.sleep(0.1)
    plt.tight_layout()
    plt.show()

screenings_names = ['No screening', "GAP SAFE (sphere)"]

import pandas as pd
df = pd.DataFrame(times.T, columns=screenings_names)

fig, ax = plt.subplots(1, 1, figsize=(9, 6))
df.plot(kind='bar', ax=ax)
plt.xticks(range(len(tols)), [str(t) for t in tols])
plt.xlabel("-log10(duality gap)")
plt.ylabel("Time (s)")
plt.title("Lasso on %s" % dataset_name)
plt.show()
time.sleep(0.2)
plt.tight_layout()
plt.show()
leg = plt.legend(frameon=True, loc='upper left')
leg.get_frame().set_alpha(0.5)

plt.savefig('img/lasso_bench_%s.png' % dataset_name)