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Fix bug in switch mixture logp #6765

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Merged
merged 1 commit into from
Jun 9, 2023
Merged

Fix bug in switch mixture logp #6765

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2 changes: 1 addition & 1 deletion pymc/logprob/mixture.py
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Original file line number Diff line number Diff line change
Expand Up @@ -344,7 +344,7 @@ def find_measurable_switch_mixture(fgraph, node):
old_mixture_rv.broadcastable,
)
new_mixture_rv = mix_op.make_node(
*([NoneConst, as_nontensor_scalar(node.inputs[0])] + components)
*([NoneConst, as_nontensor_scalar(node.inputs[0])] + components[::-1])
).default_output()

if pytensor.config.compute_test_value != "off":
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14 changes: 11 additions & 3 deletions tests/logprob/test_mixture.py
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Original file line number Diff line number Diff line change
Expand Up @@ -917,7 +917,12 @@ def test_switch_mixture():
i_vv = I_rv.clone()
i_vv.name = "i"

# When I_rv == True, X_rv flows through otherwise Y_rv does
Z1_rv = pt.switch(I_rv, X_rv, Y_rv)

assert Z1_rv.eval({I_rv: 0}) > 5
assert Z1_rv.eval({I_rv: 1}) < -5

z_vv = Z1_rv.clone()
z_vv.name = "z1"

Expand All @@ -935,7 +940,10 @@ def test_switch_mixture():

# building the identical graph but with a stack to check that mixture computations are identical

Z2_rv = pt.stack((X_rv, Y_rv))[I_rv]
Z2_rv = pt.stack((Y_rv, X_rv))[I_rv]

assert Z2_rv.eval({I_rv: 0}) > 5
assert Z2_rv.eval({I_rv: 1}) < -5

fgraph2, _, _ = construct_ir_fgraph({Z2_rv: z_vv, I_rv: i_vv})

Expand All @@ -949,8 +957,8 @@ def test_switch_mixture():
# below should follow immediately from the equal_computations assertion above
assert equal_computations([z1_logp_combined], [z2_logp_combined])

np.testing.assert_almost_equal(0.69049938, z1_logp_combined.eval({z_vv: -10, i_vv: 0}))
np.testing.assert_almost_equal(0.69049938, z2_logp_combined.eval({z_vv: -10, i_vv: 0}))
np.testing.assert_almost_equal(0.69049938, z1_logp_combined.eval({z_vv: -10, i_vv: 1}))
np.testing.assert_almost_equal(0.69049938, z2_logp_combined.eval({z_vv: -10, i_vv: 1}))


def test_ifelse_mixture_one_component():
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