bench_plot_incremental_pca.py

"""
========================
IncrementalPCA benchmark
========================

Benchmarks for IncrementalPCA

"""

import gc
from collections import defaultdict
from time import time

import matplotlib.pyplot as plt
import numpy as np

from sklearn.datasets import fetch_lfw_people
from sklearn.decomposition import PCA, IncrementalPCA


def plot_results(X, y, label):
    plt.plot(X, y, label=label, marker="o")


def benchmark(estimator, data):
    gc.collect()
    print("Benching %s" % estimator)
    t0 = time()
    estimator.fit(data)
    training_time = time() - t0
    data_t = estimator.transform(data)
    data_r = estimator.inverse_transform(data_t)
    reconstruction_error = np.mean(np.abs(data - data_r))
    return {"time": training_time, "error": reconstruction_error}


def plot_feature_times(all_times, batch_size, all_components, data):
    plt.figure()
    plot_results(all_components, all_times["pca"], label="PCA")
    plot_results(
        all_components, all_times["ipca"], label="IncrementalPCA, bsize=%i" % batch_size
    )
    plt.legend(loc="upper left")
    plt.suptitle(
        "Algorithm runtime vs. n_components\n                  LFW, size %i x %i"
        % data.shape
    )
    plt.xlabel("Number of components (out of max %i)" % data.shape[1])
    plt.ylabel("Time (seconds)")


def plot_feature_errors(all_errors, batch_size, all_components, data):
    plt.figure()
    plot_results(all_components, all_errors["pca"], label="PCA")
    plot_results(
        all_components,
        all_errors["ipca"],
        label="IncrementalPCA, bsize=%i" % batch_size,
    )
    plt.legend(loc="lower left")
    plt.suptitle("Algorithm error vs. n_components\nLFW, size %i x %i" % data.shape)
    plt.xlabel("Number of components (out of max %i)" % data.shape[1])
    plt.ylabel("Mean absolute error")


def plot_batch_times(all_times, n_features, all_batch_sizes, data):
    plt.figure()
    plot_results(all_batch_sizes, all_times["pca"], label="PCA")
    plot_results(all_batch_sizes, all_times["ipca"], label="IncrementalPCA")
    plt.legend(loc="lower left")
    plt.suptitle(
        "Algorithm runtime vs. batch_size for n_components %i\n                  LFW,"
        " size %i x %i" % (n_features, data.shape[0], data.shape[1])
    )
    plt.xlabel("Batch size")
    plt.ylabel("Time (seconds)")


def plot_batch_errors(all_errors, n_features, all_batch_sizes, data):
    plt.figure()
    plot_results(all_batch_sizes, all_errors["pca"], label="PCA")
    plot_results(all_batch_sizes, all_errors["ipca"], label="IncrementalPCA")
    plt.legend(loc="lower left")
    plt.suptitle(
        "Algorithm error vs. batch_size for n_components %i\n                  LFW,"
        " size %i x %i" % (n_features, data.shape[0], data.shape[1])
    )
    plt.xlabel("Batch size")
    plt.ylabel("Mean absolute error")


def fixed_batch_size_comparison(data):
    all_features = [
        i.astype(int) for i in np.linspace(data.shape[1] // 10, data.shape[1], num=5)
    ]
    batch_size = 1000
    # Compare runtimes and error for fixed batch size
    all_times = defaultdict(list)
    all_errors = defaultdict(list)
    for n_components in all_features:
        pca = PCA(n_components=n_components)
        ipca = IncrementalPCA(n_components=n_components, batch_size=batch_size)
        results_dict = {
            k: benchmark(est, data) for k, est in [("pca", pca), ("ipca", ipca)]
        }

        for k in sorted(results_dict.keys()):
            all_times[k].append(results_dict[k]["time"])
            all_errors[k].append(results_dict[k]["error"])

    plot_feature_times(all_times, batch_size, all_features, data)
    plot_feature_errors(all_errors, batch_size, all_features, data)


def variable_batch_size_comparison(data):
    batch_sizes = [
        i.astype(int) for i in np.linspace(data.shape[0] // 10, data.shape[0], num=10)
    ]

    for n_components in [
        i.astype(int) for i in np.linspace(data.shape[1] // 10, data.shape[1], num=4)
    ]:
        all_times = defaultdict(list)
        all_errors = defaultdict(list)
        pca = PCA(n_components=n_components)
        rpca = PCA(
            n_components=n_components, svd_solver="randomized", random_state=1999
        )
        results_dict = {
            k: benchmark(est, data) for k, est in [("pca", pca), ("rpca", rpca)]
        }

        # Create flat baselines to compare the variation over batch size
        all_times["pca"].extend([results_dict["pca"]["time"]] * len(batch_sizes))
        all_errors["pca"].extend([results_dict["pca"]["error"]] * len(batch_sizes))
        all_times["rpca"].extend([results_dict["rpca"]["time"]] * len(batch_sizes))
        all_errors["rpca"].extend([results_dict["rpca"]["error"]] * len(batch_sizes))
        for batch_size in batch_sizes:
            ipca = IncrementalPCA(n_components=n_components, batch_size=batch_size)
            results_dict = {k: benchmark(est, data) for k, est in [("ipca", ipca)]}
            all_times["ipca"].append(results_dict["ipca"]["time"])
            all_errors["ipca"].append(results_dict["ipca"]["error"])

        plot_batch_times(all_times, n_components, batch_sizes, data)
        plot_batch_errors(all_errors, n_components, batch_sizes, data)


faces = fetch_lfw_people(resize=0.2, min_faces_per_person=5)
# limit dataset to 5000 people (don't care who they are!)
X = faces.data[:5000]
n_samples, h, w = faces.images.shape
n_features = X.shape[1]

X -= X.mean(axis=0)
X /= X.std(axis=0)

fixed_batch_size_comparison(X)
variable_batch_size_comparison(X)
plt.show()