ENH: Added count parameter to unpackbits

Tests are included.

Couple of minor fixes:
- Fixed packbits/unpackbits docs to reflect proper keyword names
- Added .pytest_cache to .gitignore

1 files changed, 63 insertions, 0 deletions

diff --git a/numpy/lib/tests/test_packbits.py b/numpy/lib/tests/test_packbits.py
index fde5c37f2..00d5ca827 100644
--- a/numpy/lib/tests/test_packbits.py
+++ b/numpy/lib/tests/test_packbits.py
@@ -266,3 +266,66 @@ def test_unpackbits_large():
     assert_array_equal(np.packbits(np.unpackbits(d, axis=1), axis=1), d)
     d = d.T.copy()
     assert_array_equal(np.packbits(np.unpackbits(d, axis=0), axis=0), d)
+
+
+def test_unpackbits_count():
+    # test complete invertibility of packbits and unpackbits with count
+    x = np.array([
+        [1, 0, 1, 0, 0, 1, 0],
+        [0, 1, 1, 1, 0, 0, 0],
+        [0, 0, 1, 0, 0, 1, 1],
+        [1, 1, 0, 0, 0, 1, 1],
+        [1, 0, 1, 0, 1, 0, 1],
+        [0, 0, 1, 1, 1, 0, 0],
+        [0, 1, 0, 1, 0, 1, 0],
+    ], dtype=np.uint8)
+
+    padded1 = np.zeros(57, dtype=np.uint8)
+    padded1[:49] = x.ravel()
+
+    packed = np.packbits(x)
+    for count in range(58):
+        unpacked = np.unpackbits(packed, count=count)
+        assert_equal(unpacked.dtype, np.uint8)
+        assert_array_equal(unpacked, padded1[:count])
+    for count in range(-1, -57, -1):
+        unpacked = np.unpackbits(packed, count=count)
+        assert_equal(unpacked.dtype, np.uint8)
+        # count -1 because padded1 has 57 instead of 56 elements
+        assert_array_equal(unpacked, padded1[:count-1])
+    for kwargs in [{}, {'count': None}]:
+        unpacked = np.unpackbits(packed, **kwargs)
+        assert_equal(unpacked.dtype, np.uint8)
+        assert_array_equal(unpacked, padded1[:-1])
+    assert_raises(ValueError, np.unpackbits, packed, count=-57)
+
+    padded2 = np.zeros((9, 9), dtype=np.uint8)
+    padded2[:7, :7] = x
+
+    packed0 = np.packbits(x, axis=0)
+    packed1 = np.packbits(x, axis=1)
+    for count in range(10):
+        unpacked0 = np.unpackbits(packed0, axis=0, count=count)
+        assert_equal(unpacked0.dtype, np.uint8)
+        assert_array_equal(unpacked0, padded2[:count, :x.shape[1]])
+        unpacked1 = np.unpackbits(packed1, axis=1, count=count)
+        assert_equal(unpacked1.dtype, np.uint8)
+        assert_array_equal(unpacked1, padded2[:x.shape[1], :count])
+    for count in range(-1, -9, -1):
+        unpacked0 = np.unpackbits(packed0, axis=0, count=count)
+        assert_equal(unpacked0.dtype, np.uint8)
+        # count -1 because one extra zero of padding
+        assert_array_equal(unpacked0, padded2[:count-1, :x.shape[1]])
+        unpacked1 = np.unpackbits(packed1, axis=1, count=count)
+        assert_equal(unpacked1.dtype, np.uint8)
+        assert_array_equal(unpacked1, padded2[:x.shape[0], :count-1])
+    for kwargs in [{}, {'count': None}]:
+        unpacked0 = np.unpackbits(packed0, axis=0, **kwargs)
+        assert_equal(unpacked0.dtype, np.uint8)
+        assert_array_equal(unpacked0, padded2[:-1, :x.shape[1]])
+        unpacked1 = np.unpackbits(packed1, axis=1, **kwargs)
+        assert_equal(unpacked1.dtype, np.uint8)
+        assert_array_equal(unpacked1, padded2[:x.shape[0], :-1])
+    assert_raises(ValueError, np.unpackbits, packed0, axis=0, count=-9)
+    assert_raises(ValueError, np.unpackbits, packed1, axis=1, count=-9)
+