Removed skipna argument from count, any, all [GH755] (#4258)

* Docs: extracted skipna argument docstring for reduce [GH755]

* Added summary to whats-new.rst

Author: sjvrijn

doc/whats-new.rst

@@ -37,7 +37,8 @@ Bug fixes
 
 Documentation
 ~~~~~~~~~~~~~
-
+- removed skipna argument from :py:meth:`DataArray.count`, any, all. (:issue:`755`)
+  By `Sander van Rijn <https://github.com/sjvrijn>`_
 
 Internal Changes
 ~~~~~~~~~~~~~~~~

xarray/core/ops.py

@@ -90,12 +90,7 @@
 
 Parameters
 ----------
-{extra_args}
-skipna : bool, optional
-    If True, skip missing values (as marked by NaN). By default, only
-    skips missing values for float dtypes; other dtypes either do not
-    have a sentinel missing value (int) or skipna=True has not been
-    implemented (object, datetime64 or timedelta64).{min_count_docs}
+{extra_args}{skip_na_docs}{min_count_docs}
 keep_attrs : bool, optional
     If True, the attributes (`attrs`) will be copied from the original
     object to the new one.  If False (default), the new object will be
@@ -111,6 +106,13 @@
     indicated dimension(s) removed.
 """
 
+_SKIPNA_DOCSTRING = """
+skipna : bool, optional
+    If True, skip missing values (as marked by NaN). By default, only
+    skips missing values for float dtypes; other dtypes either do not
+    have a sentinel missing value (int) or skipna=True has not been
+    implemented (object, datetime64 or timedelta64)."""
+
 _MINCOUNT_DOCSTRING = """
 min_count : int, default None
     The required number of valid values to perform the operation.
@@ -260,6 +262,7 @@ def inject_reduce_methods(cls):
     for name, f, include_skipna in methods:
         numeric_only = getattr(f, "numeric_only", False)
         available_min_count = getattr(f, "available_min_count", False)
+        skip_na_docs = _SKIPNA_DOCSTRING if include_skipna else ""
         min_count_docs = _MINCOUNT_DOCSTRING if available_min_count else ""
 
         func = cls._reduce_method(f, include_skipna, numeric_only)
@@ -268,6 +271,7 @@ def inject_reduce_methods(cls):
             name=name,
             cls=cls.__name__,
             extra_args=cls._reduce_extra_args_docstring.format(name=name),
+            skip_na_docs=skip_na_docs,
             min_count_docs=min_count_docs,
         )
         setattr(cls, name, func)