10BC0 Merge pull request #7129 from madphysicist/percentile-midpoint-interp… · numpy/numpy@ea97756 · GitHub
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charrischarris
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Merge pull request #7129 from madphysicist/percentile-midpoint-interpolation
BUG: Fixed 'midpoint' interpolation of np.percentile in odd cases.
2 parents e36d7ca + 9ec694b commit ea97756

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‎doc/release/1.12.0-notes.rst‎

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@@ -32,10 +32,15 @@ default order for arrays that are now both.
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``MaskedArray`` takes view of data **and** mask when slicing
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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XXX
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``np.percentile`` 'midpoint' interpolation method fixed for exact indices
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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'midpoint' interpolator now gives the same result as 'lower' and 'higher' when
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the two coincide. Previous behavior of 'lower' + 0.5 is fixed.
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DeprecationWarning to error
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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‎numpy/lib/function_base.py‎

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@@ -3543,7 +3543,7 @@ def _percentile(a, q, axis=None, out=None,
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elif interpolation == 'higher':
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indices = ceil(indices).astype(intp)
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elif interpolation == 'midpoint':
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indices = floor(indices) + 0.5
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indices = 0.5 * (floor(indices) + ceil(indices))
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elif interpolation == 'nearest':
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indices = around(indices).astype(intp)
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elif interpolation == 'linear':

‎numpy/lib/tests/test_function_base.py‎

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@@ -2066,7 +2066,7 @@ def compare_results(res, desired):
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assert_array_equal(res[i], desired[i])
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class TestScoreatpercentile(TestCase):
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class TestPercentile(TestCase):
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def test_basic(self):
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x = np.arange(8) * 0.5
@@ -2115,6 +2115,10 @@ def test_lower_higher(self):
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def test_midpoint(self):
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assert_equal(np.percentile(range(10), 51,
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interpolation='midpoint'), 4.5)
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assert_equal(np.percentile(range(11), 51,
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interpolation='midpoint'), 5.5)
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assert_equal(np.percentile(range(11), 50,
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interpolation='midpoint'), 5)
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def test_nearest(self):
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assert_equal(np.percentile(range(10), 51,

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