From 00c976eabef6e62b7e33a41a0ec59e19db744246 Mon Sep 17 00:00:00 2001
From: Olivier Grisel <olivier.grisel@ensta.org>
Date: Wed, 15 Jun 2011 00:55:35 +0200
Subject: [PATCH] FIX: make the dataset doctest fixture modular
---
.gitignore | 1 +
doc/contents.rst | 2 +-
doc/datasets/index.rst | 99 +++++
doc/datasets/labeled_faces.rst | 113 ++++++
doc/datasets/labeled_faces_fixture.py | 15 +
doc/datasets/mldata.rst | 64 +++
.../mldata_fixture.py} | 17 +-
doc/datasets/twenty_newsgroups.rst | 113 ++++++
doc/datasets/twenty_newsgroups_fixture.py | 15 +
doc/modules/datasets.rst | 375 ------------------
10 files changed, 425 insertions(+), 389 deletions(-)
create mode 100644 doc/datasets/index.rst
create mode 100644 doc/datasets/labeled_faces.rst
create mode 100644 doc/datasets/labeled_faces_fixture.py
create mode 100644 doc/datasets/mldata.rst
rename doc/{modules/datasets_fixture.py => datasets/mldata_fixture.py} (73%)
create mode 100644 doc/datasets/twenty_newsgroups.rst
create mode 100644 doc/datasets/twenty_newsgroups_fixture.py
delete mode 100644 doc/modules/datasets.rst
diff --git a/.gitignore b/.gitignore
index 8793bf0e29..42dc278459 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@ dist/
doc/_build/
doc/auto_examples/
doc/modules/generated/
+doc/datasets/generated/
pip-log.txt
scikits.learn.egg-info/
.coverage
diff --git a/doc/contents.rst b/doc/contents.rst
index 48f669a7e6..cbf00302ca 100644
--- a/doc/contents.rst
+++ b/doc/contents.rst
@@ -11,6 +11,6 @@
supervised_learning.rst
unsupervised_learning.rst
model_selection.rst
- Dataset loading utilities <modules/datasets.rst>
+ Dataset loading utilities <datasets/index.rst>
Preprocessing data <modules/preprocessing.rst>
Class Reference <modules/classes.rst>
diff --git a/doc/datasets/index.rst b/doc/datasets/index.rst
new file mode 100644
index 0000000000..b5ccc3d2bc
--- /dev/null
+++ b/doc/datasets/index.rst
@@ -0,0 +1,99 @@
+..
+ For doctests:
+
+ >>> import numpy as np
+ >>> import os
+ >>> from scikits.learn import datasets
+ >>> datasets.mldata.urllib2 = mock_urllib2
+
+.. _datasets:
+
+=========================
+Dataset loading utilities
+=========================
+
+.. currentmodule:: scikits.learn.datasets
+
+The ``scikits.learn.datasets`` package embeds some small toy datasets
+as introduced in the "Getting Started" section.
+
+To evaluate the impact of the scale of the dataset (``n_samples`` and
+``n_features``) while controlling the statistical properties of the data
+(typically the correlation and informativeness of the features), it is
+also possible to generate synthetic data.
+
+This package also features helpers to fetch larger datasets commonly
+used by the machine learning community to benchmark algorithm on data
+that comes from the 'real world'.
+
+
+Datasets shipped with the scikit learn
+========================================
+
+scikit-learn comes with a few small standard datasets that do not
+require to download any file from some external website.
+
+.. autosummary::
+
+ :toctree: generated/
+ :template: function.rst
+
+ load_iris
+ load_diabetes
+ load_digits
+ load_linnerud
+
+These datasets are useful to quickly illustrate the behavior of the
+various algorithms implemented in the scikit. They are however often to
+small to be representative of real world machine learning tasks.
+
+
+Datasets in svmlight / libsvm format
+====================================
+
+scikit-learn includes a fast utility function, ``load_svmlight_format``, to load
+datasets in the svmlight / libsvm format. In this format, each line
+takes the form ``<label> <feature-id>:<feature-value>
+<feature-id>:<feature-value> ...``. This format is especially suitable for sparse datasets.
+Scipy sparse CSR matrices are used for ``X`` and numpy arrays are used for ``y``.
+
+You may load a dataset like this::
+
+ >>> from scikits.learn.datasets import load_svmlight_format
+ >>> X_train, y_train = load_svmlight_format("/path/to/train_dataset.txt")
+ ... # doctest: +SKIP
+
+You may also load two datasets at once::
+
+ >>> X_train, y_train, X_test, y_test = load_svmlight_format(
+ ... "/path/to/train_dataset.txt",
+ ... "/path/to/test_dataset.txt") # doctest: +SKIP
+
+In this case, ``X_train`` and ``X_test`` are guaranteed to have the same number
+of features. Another way to achieve the same result is to fix the number of
+features::
+
+ >>> X_test, y_test = load_svmlight_format(
+ ... "/path/to/test_dataset.txt", n_features=X_train.shape[1])
+ ... # doctest: +SKIP
+
+.. topic:: Public datasets:
+
+ _`Public datasets in svmlight / libsvm format`: http://www.csie.ntu.edu.tw/~cjlin/libsvmtools/datasets/
+
+
+.. include:: mldata.rst
+
+.. include:: twenty_newsgroups.rst
+
+.. include:: labeled_faces.rst
+
+.. todo::
+
+ Dataset generators
+ ==================
+
+ Please write some narrative documentation on how to best use the most common
+ utility functions from the ``samples_generator`` module.
+
+
diff --git a/doc/datasets/labeled_faces.rst b/doc/datasets/labeled_faces.rst
new file mode 100644
index 0000000000..89673b4cd2
--- /dev/null
+++ b/doc/datasets/labeled_faces.rst
@@ -0,0 +1,113 @@
+.. _labeled_faces_in_the_wild:
+
+The Labeled Faces in the Wild face recognition dataset
+======================================================
+
+This dataset is a collection of JPEG pictures of famous people collected
+over the internet, all details are available on the official website:
+
+ http://vis-www.cs.umass.edu/lfw/
+
+Each picture is centered on a single face. The typical task is called
+Face Verification: given a pair of two pictures, a binary classifier
+must predict whether the two images are from the same person.
+
+An alternative task, Face Recognition or Face Identification is:
+given the picture of the face of an unknown person, identify the name
+of the person by referring to a gallery of previously seen pictures of
+identified persons.
+
+Both Face Verification and Face Recognition are tasks that are typically
+performed on the output of a model trained to perform Face Detection. The
+most popular model for Face Detection is called Viola-Johns and is
+implemented in the OpenCV library. The LFW faces were extracted by this
+face detector from various online websites.
+
+
+Usage
+-----
+
+``scikit-learn`` provides two loaders that will automatically download,
+cache, parse the metadata files, decode the jpeg and convert the
+interesting slices into memmaped numpy arrays. This dataset size is more
+than 200 MB. The first load typically takes more than a couple of minutes
+to fully decode the relevant part of the JPEG files into numpy arrays. If
+the dataset has been loaded once, the following times the loading times
+less than 200ms by using a memmaped version memoized on the disk in the
+``~/scikit_learn_data/lfw_home/`` folder using ``joblib``.
+
+The first loader is used for the Face Identification task: a multi-class
+classification task (hence supervised learning)::
+
+ >>> from scikits.learn.datasets import fetch_lfw_people
+ >>> lfw_people = fetch_lfw_people(min_faces_per_person=70, resize=0.4)
+
+ >>> for name in lfw_people.target_names:
+ ... print name
+ ...
+ Ariel Sharon
+ Colin Powell
+ Donald Rumsfeld
+ George W Bush
+ Gerhard Schroeder
+ Hugo Chavez
+ Tony Blair
+
+The default slice is a rectangular shape around the face, removing
+most of the background::
+
+ >>> lfw_people.data.dtype
+ dtype('float32')
+
+ >>> lfw_people.data.shape
+ (1288, 50, 37)
+
+Each of the ``1140`` faces is assigned to a single person id in the ``target``
+array::
+
+ >>> lfw_people.target.shape
+ (1288,)
+
+ >>> list(lfw_people.target[:10])
+ [5, 6, 3, 1, 0, 1, 3, 4, 3, 0]
+
+The second loader is typically used for the face verification task: each sample
+is a pair of two picture belonging or not to the same person::
+
+ >>> from scikits.learn.datasets import fetch_lfw_pairs
+ >>> lfw_pairs_train = fetch_lfw_pairs(subset='train')
+
+ >>> list(lfw_pairs_train.target_names)
+ ['Different persons', 'Same person']
+
+ >>> lfw_pairs_train.data.shape
+ (2200, 2, 62, 47)
+
+ >>> lfw_pairs_train.target.shape
+ (2200,)
+
+Both for the ``fetch_lfw_people`` and ``fetch_lfw_pairs`` function it is
+possible to get an additional dimension with the RGB color channels by
+passing ``color=True``, in that case the shape will be
+``(2200, 2, 62, 47, 3)``.
+
+The ``fetch_lfw_pairs`` datasets is subdived in 3 subsets: the development
+``train`` set, the development ``test`` set and an evaluation ``10_folds``
+set meant to compute performance metrics using a 10-folds cross
+validation scheme.
+
+.. topic:: References:
+
+ * `Labeled Faces in the Wild: A Database for Studying Face Recognition
+ in Unconstrained Environments.
+ <http://vis-www.cs.umass.edu/lfw/lfw.pdf>`_
+ Gary B. Huang, Manu Ramesh, Tamara Berg, and Erik Learned-Miller.
+ University of Massachusetts, Amherst, Technical Report 07-49, October, 2007.
+
+
+Examples
+--------
+
+:ref:`example_applications_face_recognition.py`
+
+
diff --git a/doc/datasets/labeled_faces_fixture.py b/doc/datasets/labeled_faces_fixture.py
new file mode 100644
index 0000000000..ac15044f1c
--- /dev/null
+++ b/doc/datasets/labeled_faces_fixture.py
@@ -0,0 +1,15 @@
+"""Fixture module to skip the datasets loading when offline
+
+Doctests are skipped if the datasets have not already been dowloaded
+and cached in the past.
+"""
+from os.path import exists
+from os.path import join
+from nose import SkipTest
+from scikits.learn.datasets import get_data_home
+
+
+def setup_module(module):
+ data_home = get_data_home()
+ if not exists(join(data_home, 'lfw_home')):
+ raise SkipTest("Skipping dataset loading doctests")
diff --git a/doc/datasets/mldata.rst b/doc/datasets/mldata.rst
new file mode 100644
index 0000000000..12d824b2a2
--- /dev/null
+++ b/doc/datasets/mldata.rst
@@ -0,0 +1,64 @@
+Downloading datasets from the mldata.org repository
+===================================================
+
+`mldata.org <http://mldata.org>`_ is a public repository for machine learning
+data, supported by the `PASCAL network <http://www.pascal-network.org>`_ .
+
+The ``scikits.learn.datasets`` package is able to directly download data
+sets from the repository using the function ``fetch_mldata(dataname)``.
+
+For example, to download the MNIST digit recognition database::
+
+ >>> from scikits.learn.datasets import fetch_mldata
+ >>> mnist = fetch_mldata('MNIST original', data_home=custom_data_home)
+
+The MNIST database contains a total of 70000 examples of handwritten digits
+of size 28x28 pixels, labeled from 0 to 9::
+
+ >>> mnist.data.shape
+ (70000, 784)
+ >>> mnist.target.shape
+ (70000,)
+ >>> np.unique(mnist.target)
+ array([ 0., 1., 2., 3., 4., 5., 6., 7., 8., 9.])
+
+After the first download, the dataset is cached locally in the path
+specified by the ``data_home`` keyword argument, which defaults to
+``~/scikit_learn_data/``::
+
+ >>> os.listdir(os.path.join(custom_data_home, 'mldata'))
+ ['mnist-original.mat']
+
+Data sets in `mldata.org <http://mldata.org>`_ do not adhere to a strict
+naming or formatting convention. ``fetch_mldata`` is able to make sense
+of the most common cases, but allows to tailor the defaults to individual
+datasets:
+
+* The data arrays in `mldata.org <http://mldata.org>`_ are most often
+ shaped as ``(n_features, n_samples)``. This is the opposite of the
+ ``scikits.learn`` convention, so ``fetch_mldata`` transposes the matrix
+ by default. The ``transpose_data`` keyword controls this behavior::
+
+ >>> iris = fetch_mldata('iris', data_home=custom_data_home)
+ >>> iris.data.shape
+ (150, 4)
+ >>> iris = fetch_mldata('iris', transpose_data=False,
+ ... data_home=custom_data_home)
+ >>> iris.data.shape
+ (4, 150)
+
+* For datasets with multiple columns, ``fetch_mldata`` tries to identify
+ the target and data columns and rename them to ``target`` and ``data``.
+ This is done by looking for arrays named ``label`` and ``data`` in the
+ dataset, and failing that by choosing the first array to be ``target``
+ and the second to be ``data``. This behavior can be changed with the
+ ``target_name`` and ``data_name`` keywords, setting them to a specific
+ name or index number (the name and order of the columns in the datasets
+ can be found at its `mldata.org <http://mldata.org>`_ under the tab "Data"::
+
+ >>> iris2 = fetch_mldata('datasets-UCI iris', target_name=1, data_name=0,
+ ... data_home=custom_data_home)
+ >>> iris3 = fetch_mldata('datasets-UCI iris', target_name='class',
+ ... data_name='double0', data_home=custom_data_home)
+
+
diff --git a/doc/modules/datasets_fixture.py b/doc/datasets/mldata_fixture.py
similarity index 73%
rename from doc/modules/datasets_fixture.py
rename to doc/datasets/mldata_fixture.py
index ae2cbd0440..192daa4af5 100644
--- a/doc/modules/datasets_fixture.py
+++ b/doc/datasets/mldata_fixture.py
@@ -1,20 +1,18 @@
"""Fixture module to skip the datasets loading when offline
-Doctests are skipped if the datasets have not already been dowloaded
-and cached in the past.
+Mock urllib2 access to mldata.org
"""
-from os.path import exists
-from os.path import join
+
from os import makedirs
-from nose import SkipTest
+from os.path import join
from scikits.learn import datasets
-from scikits.learn.datasets import get_data_home
from scikits.learn.utils.testing import mock_urllib2
import tempfile
import scipy as sp
import shutil
+
def globs(globs):
# setup mock urllib2 module to avoid downloading from mldata.org
mock_datasets = {
@@ -43,13 +41,6 @@ def globs(globs):
return globs
-def setup_module(module):
- data_home = get_data_home()
- if (not exists(join(data_home, 'lfw_home'))
- or not exists(join(data_home, '20news_home'))):
- raise SkipTest("Skipping dataset loading doctests")
-
-
def teardown_module(module):
datasets.mldata.urllib2 = _urllib2_ref
shutil.rmtree(custom_data_home)
diff --git a/doc/datasets/twenty_newsgroups.rst b/doc/datasets/twenty_newsgroups.rst
new file mode 100644
index 0000000000..e1116eeb54
--- /dev/null
+++ b/doc/datasets/twenty_newsgroups.rst
@@ -0,0 +1,113 @@
+The 20 newsgroups text dataset
+==============================
+
+The 20 newsgroups dataset comprises around 18000 newsgroups posts on
+20 topics splitted in two subsets: one for training (or development)
+and the other one for testing (or for performance evaluation). The split
+between the train and test set is based upon a messages posted before
+and after a specific date.
+
+The 20 newsgroups dataset is also available through the generic
+``mldata`` dataset loader introduced earlier. However mldata
+provides a version where the data is already vectorized.
+
+This is not the case for this loader. Instead, it returns the list of
+the raw text files that can be fed to text feature extractors such as
+:class:`scikits.learn.feature_extraction.text.Vectorizer` with custom
+parameters so as to extract feature vectors.
+
+
+Usage
+-----
+
+The ``scikits.learn.datasets.fetch_20newsgroups`` function is a data
+fetching / caching functions that downloads the data archive from
+the original `20 newsgroups website`_, extracts the archive contents
+in the ``~/scikit_learn_data/20news_home`` folder and calls the
+``scikits.learn.datasets.load_filenames`` on either the training or
+testing set folder::
+
+ >>> from scikits.learn.datasets import fetch_20newsgroups
+ >>> newsgroups_train = fetch_20newsgroups(subset='train')
+
+ >>> from pprint import pprint
+ >>> pprint(list(newsgroups_train.target_names))
+ ['alt.atheism',
+ 'comp.graphics',
+ 'comp.os.ms-windows.misc',
+ 'comp.sys.ibm.pc.hardware',
+ 'comp.sys.mac.hardware',
+ 'comp.windows.x',
+ 'misc.forsale',
+ 'rec.autos',
+ 'rec.motorcycles',
+ 'rec.sport.baseball',
+ 'rec.sport.hockey',
+ 'sci.crypt',
+ 'sci.electronics',
+ 'sci.med',
+ 'sci.space',
+ 'soc.religion.christian',
+ 'talk.politics.guns',
+ 'talk.politics.mideast',
+ 'talk.politics.misc',
+ 'talk.religion.misc']
+
+The real data lies in the ``filenames`` and ``target`` attributes. The target
+attribute is the integer index of the category::
+
+ >>> newsgroups_train.filenames.shape
+ (11314,)
+ >>> newsgroups_train.target.shape
+ (11314,)
+ >>> newsgroups_train.target[:10]
+ array([12, 6, 9, 8, 6, 7, 9, 2, 13, 19])
+
+It is possible to load only a sub-selection of the categories by passing the
+list of the categories to load to the ``fetch_20newsgroups`` function::
+
+ >>> cats = ['alt.atheism', 'sci.space']
+ >>> newsgroups_train = fetch_20newsgroups(subset='train', categories=cats)
+
+ >>> list(newsgroups_train.target_names)
+ ['alt.atheism', 'sci.space']
+ >>> newsgroups_train.filenames.shape
+ (1073,)
+ >>> newsgroups_train.target.shape
+ (1073,)
+ >>> newsgroups_train.target[:10]
+ array([1, 1, 1, 0, 1, 0, 0, 1, 1, 1])
+
+In order to feed predictive or clustering models with the text data,
+one first need to turn the text into vectors of numerical values suitable
+for statistical analysis. This can be achieved with the utilities of the
+``scikits.learn.feature_extraction.text`` as demonstrated in the following
+example that extract `TF-IDF`_ vectors of unigram tokens::
+
+
+ >>> from scikits.learn.feature_extraction.text import Vectorizer
+ >>> documents = [open(f).read() for f in newsgroups_train.filenames]
+ >>> vectorizer = Vectorizer()
+ >>> vectors = vectorizer.fit_transform(documents)
+ >>> vectors.shape
+ (1073, 21108)
+
+The extracted TF-IDF vectors are very sparse with an average of 118 non zero
+components by sample in a more than 20000 dimensional space (less than 1% non
+zero features)::
+
+ >>> vectors.nnz / vectors.shape[0]
+ 118
+
+.. _`20 newsgroups website`: http://people.csail.mit.edu/jrennie/20Newsgroups/
+.. _`TF-IDF`: http://en.wikipedia.org/wiki/Tf-idf
+
+
+Examples
+--------
+
+:ref:`example_grid_search_text_feature_extraction.py`
+
+:ref:`example_document_classification_20newsgroups.py`
+
+
diff --git a/doc/datasets/twenty_newsgroups_fixture.py b/doc/datasets/twenty_newsgroups_fixture.py
new file mode 100644
index 0000000000..3c3cb50cc2
--- /dev/null
+++ b/doc/datasets/twenty_newsgroups_fixture.py
@@ -0,0 +1,15 @@
+"""Fixture module to skip the datasets loading when offline
+
+Doctests are skipped if the datasets have not already been dowloaded
+and cached in the past.
+"""
+from os.path import exists
+from os.path import join
+from nose import SkipTest
+from scikits.learn.datasets import get_data_home
+
+
+def setup_module(module):
+ data_home = get_data_home()
+ if not exists(join(data_home, '20news_home')):
+ raise SkipTest("Skipping dataset loading doctests")
diff --git a/doc/modules/datasets.rst b/doc/modules/datasets.rst
deleted file mode 100644
index a129fc8f96..0000000000
--- a/doc/modules/datasets.rst
+++ /dev/null
@@ -1,375 +0,0 @@
-..
- For doctests:
-
- >>> import numpy as np
- >>> import os
- >>> from scikits.learn import datasets
- >>> datasets.mldata.urllib2 = mock_urllib2
-
-.. _datasets:
-
-=========================
-Dataset loading utilities
-=========================
-
-.. currentmodule:: scikits.learn.datasets
-
-The ``scikits.learn.datasets`` package embeds some small toy datasets
-as introduced in the "Getting Started" section.
-
-To evaluate the impact of the scale of the dataset (``n_samples`` and
-``n_features``) while controlling the statistical properties of the data
-(typically the correlation and informativeness of the features), it is
-also possible to generate synthetic data.
-
-This package also features helpers to fetch larger datasets commonly
-used by the machine learning community to benchmark algorithm on data
-that comes from the 'real world'.
-
-
-Datasets shipped with the scikit learn
-========================================
-
-scikit-learn comes with a few small standard datasets that do not
-require to download any file from some external website.
-
-.. autosummary::
-
- :toctree: generated/
- :template: function.rst
-
- load_iris
- load_diabetes
- load_digits
- load_linnerud
-
-These datasets are useful to quickly illustrate the behavior of the
-various algorithms implemented in the scikit. They are however often to
-small to be representative of real world machine learning tasks.
-
-Datasets in svmlight / libsvm format
-====================================
-
-scikit-learn includes a fast utility function, ``load_svmlight_format``, to load
-datasets in the svmlight / libsvm format. In this format, each line
-takes the form ``<label> <feature-id>:<feature-value>
-<feature-id>:<feature-value> ...``. This format is especially suitable for sparse datasets.
-Scipy sparse CSR matrices are used for ``X`` and numpy arrays are used for ``y``.
-
-You may load a dataset like this::
-
- >>> from scikits.learn.datasets import load_svmlight_format
- >>> X_train, y_train = load_svmlight_format("/path/to/train_dataset.txt") # doctest: +SKIP
-
-You may also load two datasets at once::
-
- >>> X_train, y_train, X_test, y_test = load_svmlight_format("/path/to/train_dataset.txt",
- "/path/to/test_dataset.txt") # doctest: +SKIP
-
-In this case, ``X_train`` and ``X_test`` are guaranteed to have the same number
-of features. Another way to achieve the same result is to fix the number of
-features::
-
- >>> X_test, y_test = load_svmlight_format("/path/to/test_dataset.txt", n_features=X_train.shape[1]) # doctest: +SKIP
-
-.. topic:: Public datasets:
-
- _`Public datasets in svmlight / libsvm format`: http://www.csie.ntu.edu.tw/~cjlin/libsvmtools/datasets/
-
-
-Downloading datasets from the mldata.org repository
-===================================================
-
-`mldata.org <http://mldata.org>`_ is a public repository for machine learning
-data, supported by the `PASCAL network <http://www.pascal-network.org>`_ .
-
-The ``scikits.learn.datasets`` package is able to directly download data
-sets from the repository using the function ``fetch_mldata(dataname)``.
-
-For example, to download the MNIST digit recognition database::
-
- >>> from scikits.learn.datasets import fetch_mldata
- >>> mnist = fetch_mldata('MNIST original', data_home=custom_data_home)
-
-The MNIST database contains a total of 70000 examples of handwritten digits
-of size 28x28 pixels, labeled from 0 to 9::
-
- >>> mnist.data.shape
- (70000, 784)
- >>> mnist.target.shape
- (70000,)
- >>> np.unique(mnist.target)
- array([ 0., 1., 2., 3., 4., 5., 6., 7., 8., 9.])
-
-After the first download, the dataset is cached locally in the path
-specified by the ``data_home`` keyword argument, which defaults to
-``~/scikit_learn_data/``::
-
- >>> os.listdir(os.path.join(custom_data_home, 'mldata'))
- ['mnist-original.mat']
-
-Data sets in `mldata.org <http://mldata.org>`_ do not adhere to a strict
-naming or formatting convention. ``fetch_mldata`` is able to make sense
-of the most common cases, but allows to tailor the defaults to individual
-datasets:
-
-* The data arrays in `mldata.org <http://mldata.org>`_ are most often
- shaped as ``(n_features, n_samples)``. This is the opposite of the
- ``scikits.learn`` convention, so ``fetch_mldata`` transposes the matrix
- by default. The ``transpose_data`` keyword controls this behavior::
-
- >>> iris = fetch_mldata('iris', data_home=custom_data_home)
- >>> iris.data.shape
- (150, 4)
- >>> iris = fetch_mldata('iris', transpose_data=False,
- ... data_home=custom_data_home)
- >>> iris.data.shape
- (4, 150)
-
-* For datasets with multiple columns, ``fetch_mldata`` tries to identify
- the target and data columns and rename them to ``target`` and ``data``.
- This is done by looking for arrays named ``label`` and ``data`` in the
- dataset, and failing that by choosing the first array to be ``target``
- and the second to be ``data``. This behavior can be changed with the
- ``target_name`` and ``data_name`` keywords, setting them to a specific
- name or index number (the name and order of the columns in the datasets
- can be found at its `mldata.org <http://mldata.org>`_ under the tab "Data"::
-
- >>> iris2 = fetch_mldata('datasets-UCI iris', target_name=1, data_name=0,
- ... data_home=custom_data_home)
- >>> iris3 = fetch_mldata('datasets-UCI iris', target_name='class',
- ... data_name='double0', data_home=custom_data_home)
-
-
-The 20 newsgroups text dataset
-==============================
-
-The 20 newsgroups dataset comprises around 18000 newsgroups posts on
-20 topics splitted in two subsets: one for training (or development)
-and the other one for testing (or for performance evaluation). The split
-between the train and test set is based upon a messages posted before
-and after a specific date.
-
-The 20 newsgroups dataset is also available through the generic
-``mldata`` dataset loader introduced earlier. However mldata
-provides a version where the data is already vectorized.
-
-This is not the case for this loader. Instead, it returns the list of
-the raw text files that can be fed to text feature extractors such as
-:class:`scikits.learn.feature_extraction.text.Vectorizer` with custom
-parameters so as to extract feature vectors.
-
-
-Usage
------
-
-The ``scikits.learn.datasets.fetch_20newsgroups`` function is a data
-fetching / caching functions that downloads the data archive from
-the original `20 newsgroups website`_, extracts the archive contents
-in the ``~/scikit_learn_data/20news_home`` folder and calls the
-``scikits.learn.datasets.load_filenames`` on either the training or
-testing set folder::
-
- >>> from scikits.learn.datasets import fetch_20newsgroups
- >>> newsgroups_train = fetch_20newsgroups(subset='train')
-
- >>> from pprint import pprint
- >>> pprint(list(newsgroups_train.target_names))
- ['alt.atheism',
- 'comp.graphics',
- 'comp.os.ms-windows.misc',
- 'comp.sys.ibm.pc.hardware',
- 'comp.sys.mac.hardware',
- 'comp.windows.x',
- 'misc.forsale',
- 'rec.autos',
- 'rec.motorcycles',
- 'rec.sport.baseball',
- 'rec.sport.hockey',
- 'sci.crypt',
- 'sci.electronics',
- 'sci.med',
- 'sci.space',
- 'soc.religion.christian',
- 'talk.politics.guns',
- 'talk.politics.mideast',
- 'talk.politics.misc',
- 'talk.religion.misc']
-
-The real data lies in the ``filenames`` and ``target`` attributes. The target
-attribute is the integer index of the category::
-
- >>> newsgroups_train.filenames.shape
- (11314,)
- >>> newsgroups_train.target.shape
- (11314,)
- >>> newsgroups_train.target[:10]
- array([12, 6, 9, 8, 6, 7, 9, 2, 13, 19])
-
-It is possible to load only a sub-selection of the categories by passing the
-list of the categories to load to the ``fetch_20newsgroups`` function::
-
- >>> cats = ['alt.atheism', 'sci.space']
- >>> newsgroups_train = fetch_20newsgroups(subset='train', categories=cats)
-
- >>> list(newsgroups_train.target_names)
- ['alt.atheism', 'sci.space']
- >>> newsgroups_train.filenames.shape
- (1073,)
- >>> newsgroups_train.target.shape
- (1073,)
- >>> newsgroups_train.target[:10]
- array([1, 1, 1, 0, 1, 0, 0, 1, 1, 1])
-
-In order to feed predictive or clustering models with the text data,
-one first need to turn the text into vectors of numerical values suitable
-for statistical analysis. This can be achieved with the utilities of the
-``scikits.learn.feature_extraction.text`` as demonstrated in the following
-example that extract `TF-IDF`_ vectors of unigram tokens::
-
-
- >>> from scikits.learn.feature_extraction.text import Vectorizer
- >>> documents = [open(f).read() for f in newsgroups_train.filenames]
- >>> vectorizer = Vectorizer()
- >>> vectors = vectorizer.fit_transform(documents)
- >>> vectors.shape
- (1073, 21108)
-
-The extracted TF-IDF vectors are very sparse with an average of 118 non zero
-components by sample in a more than 20000 dimensional space (less than 1% non
-zero features)::
-
- >>> vectors.nnz / vectors.shape[0]
- 118
-
-.. _`20 newsgroups website`: http://people.csail.mit.edu/jrennie/20Newsgroups/
-.. _`TF-IDF`: http://en.wikipedia.org/wiki/Tf-idf
-
-
-Examples
---------
-
-:ref:`example_grid_search_text_feature_extraction.py`
-
-:ref:`example_document_classification_20newsgroups.py`
-
-
-.. _labeled_faces_in_the_wild:
-
-The Labeled Faces in the Wild face recognition dataset
-======================================================
-
-This dataset is a collection of JPEG pictures of famous people collected
-over the internet, all details are available on the official website:
-
- http://vis-www.cs.umass.edu/lfw/
-
-Each picture is centered on a single face. The typical task is called
-Face Verification: given a pair of two pictures, a binary classifier
-must predict whether the two images are from the same person.
-
-An alternative task, Face Recognition or Face Identification is:
-given the picture of the face of an unknown person, identify the name
-of the person by referring to a gallery of previously seen pictures of
-identified persons.
-
-Both Face Verification and Face Recognition are tasks that are typically
-performed on the output of a model trained to perform Face Detection. The
-most popular model for Face Detection is called Viola-Johns and is
-implemented in the OpenCV library. The LFW faces were extracted by this
-face detector from various online websites.
-
-
-Usage
------
-
-``scikit-learn`` provides two loaders that will automatically download,
-cache, parse the metadata files, decode the jpeg and convert the
-interesting slices into memmaped numpy arrays. This dataset size is more
-than 200 MB. The first load typically takes more than a couple of minutes
-to fully decode the relevant part of the JPEG files into numpy arrays. If
-the dataset has been loaded once, the following times the loading times
-less than 200ms by using a memmaped version memoized on the disk in the
-``~/scikit_learn_data/lfw_home/`` folder using ``joblib``.
-
-The first loader is used for the Face Identification task: a multi-class
-classification task (hence supervised learning)::
-
- >>> from scikits.learn.datasets import fetch_lfw_people
- >>> lfw_people = fetch_lfw_people(min_faces_per_person=70, resize=0.4)
-
- >>> for name in lfw_people.target_names:
- ... print name
- ...
- Ariel Sharon
- Colin Powell
- Donald Rumsfeld
- George W Bush
- Gerhard Schroeder
- Hugo Chavez
- Tony Blair
-
-The default slice is a rectangular shape around the face, removing
-most of the background::
-
- >>> lfw_people.data.dtype
- dtype('float32')
-
- >>> lfw_people.data.shape
- (1288, 50, 37)
-
-Each of the ``1140`` faces is assigned to a single person id in the ``target``
-array::
-
- >>> lfw_people.target.shape
- (1288,)
-
- >>> list(lfw_people.target[:10])
- [5, 6, 3, 1, 0, 1, 3, 4, 3, 0]
-
-The second loader is typically used for the face verification task: each sample
-is a pair of two picture belonging or not to the same person::
-
- >>> from scikits.learn.datasets import fetch_lfw_pairs
- >>> lfw_pairs_train = fetch_lfw_pairs(subset='train')
-
- >>> list(lfw_pairs_train.target_names)
- ['Different persons', 'Same person']
-
- >>> lfw_pairs_train.data.shape
- (2200, 2, 62, 47)
-
- >>> lfw_pairs_train.target.shape
- (2200,)
-
-Both for the ``fetch_lfw_people`` and ``fetch_lfw_pairs`` function it is
-possible to get an additional dimension with the RGB color channels by
-passing ``color=True``, in that case the shape will be
-``(2200, 2, 62, 47, 3)``.
-
-The ``fetch_lfw_pairs`` datasets is subdived in 3 subsets: the development
-``train`` set, the development ``test`` set and an evaluation ``10_folds``
-set meant to compute performance metrics using a 10-folds cross
-validation scheme.
-
-.. topic:: References:
-
- * `Labeled Faces in the Wild: A Database for Studying Face Recognition
- in Unconstrained Environments.
- <http://vis-www.cs.umass.edu/lfw/lfw.pdf>`_
- Gary B. Huang, Manu Ramesh, Tamara Berg, and Erik Learned-Miller.
- University of Massachusetts, Amherst, Technical Report 07-49, October, 2007.
-
-
-Examples
---------
-
-:ref:`example_applications_face_recognition.py`
-
-
-Dataset generators
-==================
-
-TODO
-
-
--
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