def test_nearest_neighbor_ranker(n_categories):
# check that we have sensible results with respect to
# NN1 binary classification (supervised, with both positive
# and negative samples)
from sklearn.neighbors import KNeighborsClassifier
from sklearn.neighbors import NearestNeighbors
np.random.seed(0)
n_samples = 110
n_features = 10
X = np.random.rand(n_samples, n_features)
normalize(X, copy=False)
index = np.arange(n_samples, dtype='int')
y = np.random.randint(0, n_categories, size=(n_samples, ))
index_train, index_test, y_train, y_test = train_test_split(index, y)
X_train = X[index_train]
X_test = X[index_test]
rk = NearestNeighborRanker()
rk.fit(X_train, y_train)
y_pred, idx_pred = rk.kneighbors(
X_test, batch_size=90) # choose a batch size smaller
# than n_samples
assert y_pred.shape == (X_test.shape[0], n_categories)
assert y_pred.min() >= -1 and y_pred.max(
) <= 1 # as we are using cosine similarities
assert idx_pred.shape == (X_test.shape[0], n_categories)
# postive scores correspond to positive documents
#assert_equal((y_pred > 0), y_train[idx])
cl = KNeighborsClassifier(n_neighbors=1,
algorithm='brute',
metric='cosine')
cl.fit(X_train, y_train)
idx_ref_cl = cl.predict(X_test)
# make sure we get the same results as for the KNeighborsClassifier
label_pred = np.argmax(y_pred, axis=1)
assert_equal(label_pred, idx_ref_cl)
nn = NearestNeighbors(n_neighbors=1, algorithm='brute', metric='cosine')
nn.fit(X_train)
S_ref_nn, idx_ref_nn = nn.kneighbors(X_test)
assert_equal(idx_pred[range(len(label_pred)), label_pred], idx_ref_nn[:,
0])
assert_allclose(np.max(y_pred, axis=1)[:, None], 1 - S_ref_nn)
def test_nearest_neighbor_ranker_is_picklable():
mod = NearestNeighborRanker()
mod.fit([[0, 1], [1, 0]], [0, 1])
try:
tmp_file = os.path.join(cache_dir, 'tmp_NearestNeighborRanker.pkl')
joblib.dump(mod, tmp_file)
mod2 = joblib.load(tmp_file)
finally:
if os.path.exists(tmp_file):
os.remove(tmp_file)