COMPAT: Add back remove_na for seaborn (pandas-dev#16992)

Closes pandas-devgh-16971.

pandas/core/series.py

@@ -37,7 +37,6 @@
     maybe_convert_platform,
     maybe_cast_to_datetime, maybe_castable)
 from pandas.core.dtypes.missing import isnull, notnull, remove_na_arraylike
-
 from pandas.core.common import (is_bool_indexer,
                                 _default_index,
                                 _asarray_tuplesafe,
@@ -88,6 +87,17 @@
     versionadded_to_excel='\n    .. versionadded:: 0.20.0\n')
 
 
+# see gh-16971
+def remove_na(arr):
+    """
+    DEPRECATED : this function will be removed in a future version.
+    """
+
+    warnings.warn("remove_na is deprecated and is a private "
+                  "function. Do not use.", FutureWarning, stacklevel=2)
+    return remove_na_arraylike(arr)
+
+
 def _coerce_method(converter):
     """ install the scalar coercion methods """
 

pandas/tests/series/test_missing.py

@@ -15,6 +15,7 @@
                     MultiIndex, Index, Timestamp, NaT, IntervalIndex)
 from pandas.compat import range
 from pandas._libs.tslib import iNaT
+from pandas.core.series import remove_na
 from pandas.util.testing import assert_series_equal, assert_frame_equal
 import pandas.util.testing as tm
 
@@ -50,6 +51,11 @@ def _simple_ts(start, end, freq='D'):
 
 class TestSeriesMissingData(TestData):
 
+    def test_remove_na_deprecation(self):
+        # see gh-16971
+        with tm.assert_produces_warning(FutureWarning):
+            remove_na(Series([]))
+
     def test_timedelta_fillna(self):
         # GH 3371
         s = Series([Timestamp('20130101'), Timestamp('20130101'), Timestamp(