DOC: Add a whatsnew entry for labeled data improvements

matplotlib · tacaswell · Sep 13, 2015 · Jul 26, 2015 · Jul 25, 2015 · Jul 26, 2015
commit 9846b9c6205b2abb902690195c0e05862c0ddf6e
diff --git a/doc/users/whats_new/2015-07-30_unpack_labeled_data.rst b/doc/users/whats_new/2015-07-30_unpack_labeled_data.rst
@@ -0,0 +1,30 @@
+Working with labeled data like pandas DataFrames
+------------------------------------------------
+Plot methods which take arrays as inputs can now also work with labeled data
+and unpack such data.
+
+This means that the following two examples produce the same plot::
+
+Example ::
+    df = pandas.DataFrame({"var1":[1,2,3,4,5,6], "var2":[1,2,3,4,5,6]})
+    plt.plot(df["var1"], df["var2"])
+
+
+Example ::
+    plt.plot("var1", "var2", data=df)
+
+This works for most plotting methods, which expect arrays/sequences as
+inputs and ``data`` can be anything which supports ``__get_item__``
+(``dict``, ``pandas.DataFrame``,...).
+
+In addition to this, some other changes were made, which makes working with
+``pandas.DataFrames`` easier:
+
+* For plotting methods which understand a ``label`` keyword argument but the
+  user does not supply such an argument, this is now implicitly set by either
+  looking up ``.name`` of the right input or by using the label supplied to
+  lookup the input in ``data``. In the above examples, this results in an
+  implicit ``label="var2"`` for both cases.
+
+* ``plot()`` now uses the index of a ``Series`` instead of
+  ``np.arange(len(y))``, if no ``x`` argument is supplied.