DOC Clarified variation in confusion_matrix axes (#11334)

maxcopeland · jnothman · commit 8083ea4a2138 · 2018-06-26T10:56:01.000+10:00
fixes #11326
diff --git a/.travis.yml b/.travis.yml
@@ -3,11 +3,11 @@ sudo: false
 
 language: python
 
-cache:
-  apt: true
-  directories:
-  - $HOME/.cache/pip
-  - $HOME/.ccache
+# cache:
+#   apt: true
+#   directories:
+#   - $HOME/.cache/pip
+#   - $HOME/.ccache
 
 dist: trusty
 
diff --git a/doc/modules/model_evaluation.rst b/doc/modules/model_evaluation.rst
@@ -523,8 +523,11 @@ Confusion matrix
 ----------------
 
 The :func:`confusion_matrix` function evaluates
-classification accuracy by computing the `confusion matrix
+classification accuracy by computing the confusion matrix
+with each row corresponding to the true class
 <https://en.wikipedia.org/wiki/Confusion_matrix>`_.
+(Wikipedia and other references may use different convention for axes.)
+
 
 By definition, entry :math:`i, j` in a confusion matrix is
 the number of observations actually in group :math:`i`, but
diff --git a/sklearn/metrics/classification.py b/sklearn/metrics/classification.py
@@ -223,6 +223,8 @@ def confusion_matrix(y_true, y_pred, labels=None, sample_weight=None):
     ----------
     .. [1] `Wikipedia entry for the Confusion matrix
            <https://en.wikipedia.org/wiki/Confusion_matrix>`_
+           (Wikipedia and other references may use a different
+           convention for axes)
 
     Examples
     --------
