8000 MAINT: Ediff1d performance by mattharrigan · Pull Request #8183 · numpy/numpy · GitHub
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MAINT: Ediff1d performance #8183

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Merged
merged 2 commits into from
Oct 24, 2016
Merged

MAINT: Ediff1d performance #8183

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16a98c0
ENH: performance improvement to ediff1d
mattharrigan Oct 19, 2016
4848271
TST: Added cases for better coverage of ediff1d
mattharrigan Oct 19, 2016
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41 changes: 27 additions & 14 deletions numpy/lib/arraysetops.py
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Original file line number Diff line number Diff line change
Expand Up @@ -78,20 +78,33 @@ def ediff1d(ary, to_end=None, to_begin=None):
array([ 1, 2, -3, 5, 18])

"""
ary = np.asanyarray(ary).flat
ed = ary[1:] - ary[:-1]
arrays = [ed]
if to_begin is not None:
arrays.insert(0, to_begin)
if to_end is not None:
arrays.append(to_end)

if len(arrays) != 1:
# We'll save ourselves a copy of a potentially large array in
# the common case where neither to_begin or to_end was given.
ed = np.hstack(arrays)

return ed
# force a 1d array
ary = np.asanyarray(ary).ravel()

# get the length of the diff'd values
l = len(ary) - 1
if l < 0:
# force length to be non negative, match previous API
# should this be an warning or deprecated?
l = 0

if to_begin is None:
to_begin = np.array([])
else:
to_begin = np.asanyarray(to_begin).ravel()

if to_end is None:
to_end = np.array([])
else:
to_end = np.asanyarray(to_end).ravel()

# do the calculation in place and copy to_begin and to_end
result = np.empty(l + len(to_begin) + len(to_end), dtype=ary.dtype)
result[:len(to_begin)] = to_begin
result[len(to_begin) + l:] = to_end
np.subtract(ary[1:], ary[:-1], result[len(to_begin):len(to_begin) + l])
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Surely this is wrong? It always writes only one element of the output!

return result


def unique(ar, return_index=False, return_inverse=False, return_counts=False):
"""
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6 changes: 6 additions & 0 deletions numpy/lib/tests/test_arraysetops.py
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Original file line number Diff line number Diff line change
Expand Up @@ -169,6 +169,12 @@ def test_ediff1d(self):
assert_array_equal([-1, 0], ediff1d(zero_elem, to_begin=-1, to_end=0))
assert_array_equal([], ediff1d(one_elem))
assert_array_equal([1], ediff1d(two_elem))
assert_array_equal([7,1,9], ediff1d(two_elem, to_begin=7, to_end=9))
assert_array_equal([5,6,1,7,8], ediff1d(two_elem, to_begin=[5,6], to_end=[7,8]))
assert_array_equal([1,9], ediff1d(two_elem, to_end=9))
assert_array_equal([1,7,8], ediff1d(two_elem, to_end=[7,8]))
assert_array_equal([7,1], ediff1d(two_elem, to_begin=7))
assert_array_equal([5,6,1], ediff1d(two_elem, to_begin=[5,6]))

def test_in1d(self):
# we use two different sizes for the b array here to test the
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0