[GitHub] [arrow] pitrou commented on a change in pull request #8163: ARROW-9465: [Python] Improve ergonomics of compute module

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

pitrou commented on a change in pull request #8163:
URL: https://github.com/apache/arrow/pull/8163#discussion_r487912471



##########
File path: python/pyarrow/_compute.pyx
##########
@@ -140,6 +162,29 @@ cdef class ScalarAggregateKernel(Kernel):
 
 
 cdef class Function(_Weakrefable):
+    """
+    A compute function.
+
+    A function implements a certain logical computation over a range of
+    possible input signatures.  Each signature accepts a range of input
+    types and is implemented by a given Kernel.
+
+    Functions can be of different kinds:
+
+    * "scalar" functions apply an item-wise computation over all items
+      of their inputs.  Each item in the output only depends on the values
+      of the inputs at the same position.  Examples: addition, comparisons,
+      string predicates...
+
+    * "vector" functions apply a collection-wise computation, such that
+      each item in the output may depend on the values of several items
+      in each input.  Examples: dictionary encoding, sorting, extracting
+      unique values...
+
+    * "aggregate" functions reduce the dimensionality of the inputs by
+      applying a reduction function.  Examples: sum, minmax, mode...
+

Review comment:
       Yes, you're right.




----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org