From 61b3753b658ab726c214d40f3faa1f9de4b0ff27 Mon Sep 17 00:00:00 2001
From: Gael varoquaux <gael.varoquaux@normalesup.org>
Date: Tue, 23 Nov 2010 09:21:30 +0100
Subject: [PATCH] ENH: Raise error when cloning bug estimators
Estimators with non conformant __init__ don't clone right. This prevents
cross_val from working, and leads to highly non-trivial bugs. Detect it
in clone and raise an error in this case.
---
scikits/learn/base.py | 4 ++++
scikits/learn/tests/test_base.py | 10 ++++++++++
2 files changed, 14 insertions(+)
diff --git a/scikits/learn/base.py b/scikits/learn/base.py
index fccd43759b..a78679f52d 100644
--- a/scikits/learn/base.py
+++ b/scikits/learn/base.py
@@ -46,6 +46,10 @@ def clone(estimator, safe=True):
for name, param in new_object_params.iteritems():
new_object_params[name] = clone(param, safe=False)
new_object = klass(**new_object_params)
+ assert new_object._get_params(deep=False) == new_object_params, (
+ 'Cannot clone object %s, as the constructor does not '
+ 'seem to set parameters' % estimator
+ )
return new_object
diff --git a/scikits/learn/tests/test_base.py b/scikits/learn/tests/test_base.py
index 074c70bb2c..53a422f5cb 100644
--- a/scikits/learn/tests/test_base.py
+++ b/scikits/learn/tests/test_base.py
@@ -23,6 +23,11 @@ class T(BaseEstimator):
self.a = a
self.b = b
+class Buggy(BaseEstimator):
+ " A buggy estimator that does not set its parameters right. "
+
+ def __init__(self, a=None):
+ self.a = 1
################################################################################
# The tests
@@ -58,6 +63,11 @@ def test_clone_2():
new_selector = clone(selector)
assert_false(hasattr(new_selector, "own_attribute"))
+def test_clone_buggy():
+ """ Check that clone raises an error on buggy estimators """
+ buggy = Buggy()
+ buggy.a = 2
+ assert_raises(AssertionError, clone, buggy)
def test_repr():
""" Smoke test the repr of the
--
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