Add "rename" method

docs/index.rst

@@ -87,6 +87,19 @@ define will appear on the ``.ak`` accessor or can be used for ufunc and
 operator overloads.
 
 
+Sub-accessors
+~~~~~~~~~~~~~
+
+As an alternative to the object-oriented behaviours, developers may create
+accessor namespaces that appear under ``.ak`` similar to the the builtin
+``.ak.str`` (strings ops) snd ``.ak.dt`` (datetime ops) included already.
+
+One experimental proof-of-concept is `akimbo-ip`_, which provides fast vectorised
+manipulations of IPv4/6 addresses and networks; and by using this through
+the ``akimbo`` system, you can apply these methods to ragged/nested dataframes.
+
+.. _akimbo-ip: https://github.com/intake/akimbo-ip
+
 .. toctree::
    :maxdepth: 1
    :caption: User Guide

src/akimbo/mixin.py

@@ -232,6 +232,30 @@ def register_accessor(cls, name, klass):
         # TODO: check clobber?
         cls.subaccessors[name] = klass
 
+    def rename(self, where, to):
+        """Assign new field name to given location in the structure
+
+        Parameters
+        ----------
+        where: str | tuple[str]
+            location we would like to rename
+        to: str
+            new name
+        """
+        arr = self.array
+        lay = ak.copy(arr.layout)
+        where = list(where) if isinstance(where, tuple) else [where]
+        parent = None
+        bit = lay
+        while where:
+            if getattr(bit, "contents", None):
+                this = bit.fields.index(where.pop(0))
+                parent, bit = bit, bit.contents[this]
+            else:
+                parent, bit = bit, bit.content
+        parent.fields[this] = to
+        return self.to_output(ak.Array(lay))
+
     def merge(self):
         """Make a single complex series out of the columns of a dataframe"""
         if not self.is_dataframe(self._obj):

tests/test_pandas.py

@@ -56,3 +56,17 @@ def test_to_autoarrow():
     s2 = s.ak.to_output()
     assert s2.tolist() == a
     assert "pyarrow" in str(s2.dtype)
+
+
+def test_rename():
+    a = [{"a": [{"b": {"c": 0}}] * 2}] * 3
+    s = pd.Series(a)
+
+    s2 = s.ak.rename(("a", "b"), "d")
+    assert s2.tolist() == [{"a": [{"d": {"c": 0}}] * 2}] * 3
+
+    s2 = s.ak.rename("a", "d")
+    assert s2.tolist() == [{"d": [{"b": {"c": 0}}] * 2}] * 3
+
+    s2 = s.ak.rename(("a", "b", "c"), "d")
+    assert s2.tolist() == [{"a": [{"b": {"d": 0}}] * 2}] * 3