BUG: stats: Fix zipf.pmf and zipfian.pmf for int32 k#20702
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dschmitz89 merged 3 commits intoscipy:mainfrom May 20, 2024
Merged
BUG: stats: Fix zipf.pmf and zipfian.pmf for int32 k#20702dschmitz89 merged 3 commits intoscipy:mainfrom
zipf.pmf and zipfian.pmf for int32 k#20702dschmitz89 merged 3 commits intoscipy:mainfrom
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zipf.pmf for integer kzipf.pmf for int32 k
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scipy/scipy/stats/_discrete_distns.py Line 1415 in 2f16622 I am not familiar with these distributions though and could not cook up a failing example in a quick session, so let me know if this would be important to fix as well. |
| dist = zipf(9) | ||
| pmf = dist.pmf(k) | ||
| pmf_k_int32 = dist.pmf(k_int32) | ||
| assert_equal(pmf, pmf_k_int32) No newline at end of file |
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Hey Daniel, I just messed around for a bit and found this case that failed before/passed after a similar patch per your comment on zipfian:
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diff --git a/scipy/stats/_discrete_distns.py b/scipy/stats/_discrete_distns.py
index cda7c4e11..2ee610827 100644
--- a/scipy/stats/_discrete_distns.py
+++ b/scipy/stats/_discrete_distns.py
@@ -1412,7 +1412,8 @@ class zipfian_gen(rv_discrete):
return 1, n
def _pmf(self, k, a, n):
- return 1.0 / _gen_harmonic(n, a) / k**a
+ k = k.astype(np.float64)
+ return 1.0 / _gen_harmonic(n, a) * k**-a
def _cdf(self, k, a, n):
return _gen_harmonic(k, a) / _gen_harmonic(n, a)
diff --git a/scipy/stats/tests/test_discrete_distns.py b/scipy/stats/tests/test_discrete_distns.py
index c5993ebde..bbe9085ce 100644
--- a/scipy/stats/tests/test_discrete_distns.py
+++ b/scipy/stats/tests/test_discrete_distns.py
@@ -627,3 +627,12 @@ class TestBetaNBinom:
# return float(fourth_moment/var**2 - 3.)
assert_allclose(betanbinom.stats(n, a, b, moments="k"),
ref, rtol=3e-15)
+
+
+def test_zipfian_gh_20692():
+ k = np.arange(0, 1000)
+ k_int32 = k.astype(np.int32)
+ dist = zipfian(111, 22)
+ pmf = dist.pmf(k)
+ pmf_k_int32 = dist.pmf(k_int32)
+ assert_equal(pmf, pmf_k_int32)You shouldn't trust my judgement on stats stuff, but it does look quite similar in nature as you note. The obtained pmf floats are ridiculously tiny, maybe 111 is a bit much, but anyway I just pushed it to error out for integers. It does run lightning fast at least.
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Added in the last commit.
Co-authored-by: Tyler Reddy <tyler.je.reddy@gmail.com>
zipf.pmf for int32 kzipf.pmf and zipfian.pmf for int32 k
zipf.pmf and zipfian.pmf for int32 kzipf.pmf and zipfian.pmf for int32 k
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I went ahead and merged this since it is a quite simple bug fix. |
tylerjereddy
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May 22, 2024
…) [wheel build] * BUG: fix zipf.pmf for integer k * ENH: increase range for zipfian.pmf for integer k --------- Co-authored-by: Tyler Reddy <tyler.je.reddy@gmail.com> [wheel build]
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Reference issue
Closes gh-20692
In the long run, these issues should hopefully be taken care of by the infrastructure (#15928 ).