From e0f22a99bf3e9af38023a38d7f034d9fbafe871a Mon Sep 17 00:00:00 2001
From: martin-hahn <martin.hahn@blue-yonder.com>
Date: Thu, 30 Mar 2017 14:14:02 +0200
Subject: [PATCH] [MRG+1] Calculate confidence intervall only if we have enough
samples (#8621)
* calculate confidence intervall only if we have enough samples
* pep8
* removed parentheses
---
sklearn/isotonic.py | 2 +-
sklearn/tests/test_isotonic.py | 8 ++++++++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/sklearn/isotonic.py b/sklearn/isotonic.py
index f3e86b9813..910c235085 100644
--- a/sklearn/isotonic.py
+++ b/sklearn/isotonic.py
@@ -57,7 +57,7 @@ def check_increasing(x, y):
increasing_bool = rho >= 0
# Run Fisher transform to get the rho CI, but handle rho=+/-1
- if rho not in [-1.0, 1.0]:
+ if rho not in [-1.0, 1.0] and len(x) > 3:
F = 0.5 * math.log((1. + rho) / (1. - rho))
F_se = 1 / math.sqrt(len(x) - 3)
diff --git a/sklearn/tests/test_isotonic.py b/sklearn/tests/test_isotonic.py
index 7abadaf562..d5d0715a0f 100644
--- a/sklearn/tests/test_isotonic.py
+++ b/sklearn/tests/test_isotonic.py
@@ -27,6 +27,14 @@ def test_permutation_invariance():
assert_array_equal(y_transformed, y_transformed_s)
+def test_check_increasing_small_number_of_samples():
+ x = [0, 1, 2]
+ y = [1, 1.1, 1.05]
+
+ is_increasing = assert_no_warnings(check_increasing, x, y)
+ assert_true(is_increasing)
+
+
def test_check_increasing_up():
x = [0, 1, 2, 3, 4, 5]
y = [0, 1.5, 2.77, 8.99, 8.99, 50]
--
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