[GitHub] [arrow] lidavidm commented on a change in pull request #7027: ARROW-8572: [Python] expose UnionArray fields to Python

[GitBox <gi...@apache.org>]

lidavidm commented on a change in pull request #7027:
URL: https://github.com/apache/arrow/pull/7027#discussion_r416559505



##########
File path: python/pyarrow/array.pxi
##########
@@ -1720,6 +1720,39 @@ cdef class UnionArray(Array):
     Concrete class for Arrow arrays of a Union data type.
     """
 
+    def child(self, int pos):
+        """
+        Return the given child array as an individual array.
+
+        For sparse unions, the returned array has its offset, length,
+        and null count adjusted.
+
+        For dense unions, the returned array is unchanged.
+        """
+        cdef shared_ptr[CArray] result
+        result = (<CUnionArray*> self.ap).child(pos)
+        if result != NULL:
+            return pyarrow_wrap_array(result)
+        raise KeyError("UnionArray does not have child {}".format(pos))
+
+    @property
+    def type_codes(self):
+        """Get the type codes array."""
+        buf = pyarrow_wrap_buffer((<CUnionArray*> self.ap).type_codes())
+        return Array.from_buffers(int8(), len(self), [None, buf])
+
+    @property
+    def value_offsets(self):

Review comment:
       Thanks for the review! I renamed this to 'offsets' to be consistent with Python.




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