8000 Merge pull request #7346 from erensezener/generalized_flip · numpy/numpy@5b91628 · GitHub
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charrischarris
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Merge pull request #7346 from erensezener/generalized_flip
Generalized flip
2 parents f98b59e + e7de401 commit 5b91628

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‎doc/release/1.12.0-notes.rst

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@@ -99,6 +99,12 @@ keyword argument. It can be set to False when no write operation
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to the returned array is expected to avoid accidental
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unpredictable writes.
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Generalized ``flip``
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~~~~~~~~~~~~~~~~~~~~
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``flipud`` and ``fliplr`` reverse the elements of an array along axis=0 and
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axis=1 respectively. The newly added ``flip`` function reverses the elements of
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an array along any given axis.
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BLIS support in ``numpy.distutils``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

‎doc/source/reference/routines.array-manipulation.rst

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@@ -109,6 +109,7 @@ Rearranging elements
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.. autosummary::
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:toctree: generated/
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flip
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fliplr
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flipud
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reshape

‎numpy/lib/function_base.py

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@@ -36,7 +36,7 @@
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__all__ = [
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'select', 'piecewise', 'trim_zeros', 'copy', 'iterable', 'percentile',
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'diff', 'gradient', 'angle', 'unwrap', 'sort_complex', 'disp',
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'diff', 'gradient', 'angle', 'unwrap', 'sort_complex', 'disp', 'flip',
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'extract', 'place', 'vectorize', 'asarray_chkfinite', 'average',
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'histogram', 'histogramdd', 'bincount', 'digitize', 'cov', 'corrcoef',
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'msort', 'median', 'sinc', 'hamming', 'hanning', 'bartlett',
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]
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def flip(m, axis):
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"""
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Reverse the order of elements in an array along the given axis.
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The shape of the array is preserved, but the elements are reordered.
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.. versionadded:: 1.12.0
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Parameters
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----------
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m : array_like
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Input array.
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axis: integer
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Axis in array, which entries are reversed.
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Returns
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-------
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out : array_like
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A view of `m` with the entries of axis reversed. Since a view is
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returned, this operation is done in constant time.
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See Also
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--------
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flipud : Flip an array vertically (axis=0).
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fliplr : Flip an array horizontally (axis=1).
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Notes
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-----
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flip(m, 0) is equivalent to flipud(m).
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flip(m, 1) is equivalent to fliplr(m).
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flip(m, n) corresponds to ``m[...,::-1,...]`` with ``::-1`` at position n.
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Examples
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--------
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>>> A = np.arange(8).reshape((2,2,2))
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>>> A
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array([[[0, 1],
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[2, 3]],
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[[4, 5],
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[6, 7]]])
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>>> flip(A, 0)
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array([[[4, 5],
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[6, 7]],
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[[0, 1],
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[2, 3]]])
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>>> flip(A, 1)
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array([[[2, 3],
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[0, 1]],
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[[6, 7],
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[4, 5]]])
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>>> A = np.random.randn(3,4,5)
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>>> np.all(flip(A,2) == A[:,:,::-1,...])
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True
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"""
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if not hasattr(m, 'ndim'):
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m = asarray(m)
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indexer = [slice(None)] * m.ndim
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try:
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indexer[axis] = slice(None, None, -1)
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except IndexError:
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raise ValueError("axis=%i is invalid for the %i-dimensional input array"
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% (axis, m.ndim))
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return m[tuple(indexer)]
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def iterable(y):
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"""
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Check whether or not an object can be iterated over.

‎numpy/lib/tests/test_function_base.py

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from numpy.compat import long
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def get_mat(n):
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data = np.arange(n)
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data = np.add.outer(data, data)
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return data
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class TestFlip(TestCase):
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def test_axes(self):
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self.assertRaises(ValueError, np.flip, np.ones(4), axis=1)
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self.assertRaises(ValueError, np.flip, np.ones((4, 4)), axis=2)
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self.assertRaises(ValueError, np.flip, np.ones((4, 4)), axis=-3)
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def test_basic_lr(self):
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a = get_mat(4)
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b = a[:, ::-1]
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assert_equal(np.flip(a, 1), b)
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a = [[0, 1, 2],
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[3, 4, 5]]
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b = [[2, 1, 0],
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[5, 4, 3]]
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assert_equal(np.flip(a, 1), b)
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def test_basic_ud(self):
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a = get_mat(4)
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b = a[::-1, :]
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assert_equal(np.flip(a, 0), b)
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a = [[0, 1, 2],
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[3, 4, 5]]
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b = [[3, 4, 5],
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[0, 1, 2]]
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assert_equal(np.flip(a, 0), b)
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def test_3d_swap_axis0(self):
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a = np.array([[[0, 1],
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[2, 3]],
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[[4, 5],
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[6, 7]]])
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b = np.array([[[4, 5],
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[6, 7]],
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[[0, 1],
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[2, 3]]])
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assert_equal(np.flip(a, 0), b)
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def test_3d_swap_axis1(self):
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a = np.array([[[0, 1],
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[2, 3]],
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[[4, 5],
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[6, 7]]])
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b = np.array([[[2, 3],
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[0, 1]],
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[[6, 7],
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[4, 5]]])
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assert_equal(np.flip(a, 1), b)
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def test_3d_swap_axis2(self):
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a = np.array([[[0, 1],
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[2, 3]],
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[[4, 5],
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[6, 7]]])
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b = np.array([[[1, 0],
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[3, 2]],
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[[5, 4],
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[7, 6]]])
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assert_equal(np.flip(a, 2), b)
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def test_4d(self):
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a = np.arange(2 * 3 * 4 * 5).reshape(2, 3, 4, 5)
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for i in range(a.ndim):
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assert_equal(np.flip(a, i), np.flipud(a.swapaxes(0, i)).swapaxes(i, 0))
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class TestAny(TestCase):
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def test_basic(self):

‎numpy/lib/twodim_base.py

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@@ -57,7 +57,7 @@ def fliplr(m):
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Notes
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-----
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Equivalent to A[:,::-1]. Requires the array to be at least 2-D.
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Equivalent to m[:,::-1]. Requires the array to be at least 2-D.
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Examples
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--------
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[ 3., 0., 0.]])
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>>> A = np.random.randn(2,3,5)
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>>> np.all(np.fliplr(A)==A[:,::-1,...])
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>>> np.all(np.fliplr(A) == A[:,::-1,...])
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True
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"""
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Notes
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-----
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Equivalent to ``A[::-1,...]``.
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Equivalent to ``m[::-1,...]``.
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Does not require the array to be two-dimensional.
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Examples
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[ 1., 0., 0.]])
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>>> A = np.random.randn(2,3,5)
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>>> np.all(np.flipud(A)==A[::-1,...])
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>>> np.all(np.flipud(A) == A[::-1,...])
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True
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>>> np.flipud([1,2])

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