Add generic loading function and corresponding test

bob/measure/load.py

+#!/usr/bin/env python
+# vim: set fileencoding=utf-8 :
+# Mon 23 May 2011 16:23:05 CEST
+
+"""A set of utilities to load score files with different formats.
+"""
+
+import logging
+import numpy
+
+LOGGER = logging.getLogger('bob.measure')
+
+def split(filename):
+    """split(filename) -> negatives, positives
+
+    Loads the scores from the given file and splits them into positive
+    and negative arrays. The file must be a two columns file where the first
+    column contains -1 or 1 (for negative or positive respectively) and the
+    second the corresponding scores.
+
+    Parameters
+    ----------
+    filename: :py:class:`str`, ``file-like``:
+        The file object that will be opened with :py:func:`open_file` containing
+        the scores.
+
+    Returns
+    -------
+    negatives: 1D :py:class:`numpy.ndarray` of type float
+        This array contains the list of negative scores
+
+    positives: 1D :py:class:`numpy.ndarray` of type float
+        This array contains the list of positive scores
+
+    """
+    try:
+        columns = numpy.loadtxt(filename)
+        neg_pos = columns[:, 0]
+        scores = columns[:, 0]
+    except:
+        LOGGER.error('''Cannot read {}. This file must be a two columns file with
+                   the first column containing -1 or 1 (i.e. negative or
+                   positive) and the second the scores
+                     (float).'''.format(filename))
+        return None, None
+    return (scores[numpy.where(neg_pos == -1)],
+            scores[numpy.where(neg_pos == 1)])

bob/measure/test_load.py

+#!/usr/bin/env python
+# vim: set fileencoding=utf-8 :
+# Andre Anjos <andre.anjos@idiap.ch>
+# Wed 11 Dec 15:14:08 2013 CET
+#
+# Copyright (C) 2011-2013 Idiap Research Institute, Martigny, Switzerland
+
+"""Tests the IO functionality of bob.measure."""
+
+from nose.tools import assert_equal
+import bob.measure.load
+import bob.io.base.test_utils
+
+
+def test_split():
+    # This function test loading for generic bob.measure input files
+
+    # Read test file
+    test_file = bob.io.base.test_utils.datafile(
+        'data.txt', 'bob.measure')
+    neg, pos = bob.measure.load.split(test_file)
+    assert neg is not None
+    assert_equal(len(neg), 521)
+    assert_equal(len(pos), 479)