The following code based on the failing test reproduces the issue on an i386 porterbox:
***
from sklearn.tree import (
DecisionTreeClassifier,
export_graphviz,
)
import pdb
X = [[-2, -1], [-1, -1], [-1, -2], [1, 1], [1, 2], [2, 1]]
y2 = [[-1, 1], [-1, 1], [-1, 1], [1, 2], [1, 2], [1, 3]]
w = [1, 1, 1, 0.5, 0.5, 0.5]
def main():
clf = DecisionTreeClassifier(
max_depth=2, min_samples_split=2, criterion="gini", random_state=2
)
clf = clf.fit(X, y2, sample_weight=w)
pdb.set_trace()
contents1 = export_graphviz(clf, filled=True, impurity=False, out_file=None)
if __name__ == "__main__":
main()
***
On an amd64 system, we see the following normal behavior when inspecting
`clf.tree_` and its negation at the given breakpoint:
> (Pdb) clf.tree_.impurity
> array([0.4691358 , 0. , 0.22222222, 0. , 0. ])
> (Pdb) -clf.tree_.impurity
> array([-0.4691358 , -0. , -0.22222222, -0. , -0. ])
However, on an i386 porterbox, we get this funny behavior with the
negation:
> (Pdb) clf.tree_.impurity
> array([0.4691358 , 0. , 0.22222222, 0. , 0. ])
> (Pdb) -clf.tree_.impurity
> array([-4.69135802e-001, -1.59149684e-314, -1.50000000e+000,
> -2.12199579e-314, nan])
This smells of some alignment issue on an FFI boundary, perhaps. It
certainly explains the failing test (as the tested code does `np.min`
and `np.max` of `-clf.tree_.impurity`).
Best,
Gard
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