Hello Mura, You can also take a look at the compute registration example [1], [2] in the Arrow source code to get an idea how to write a custom function and use it in C++. Assuming your objective is to add a new function to C++ permanently and use it in Python, you may need to take a look at the existing Python-bindings.
For instance take a look at the Join operator exposure [3]-[8]. This is not a full list of references to all the components. But I hope you can get an idea about exposing a function from C++ to Python. In addition, if you just need a function to be used in Python (user-defined-function), you can do everything in Python as well. For that you may take a look at [9], [10]. Please note that this feature is experimental and work in progress. [1]. Compute Example: https://github.com/apache/arrow/blob/master/cpp/examples/arrow/compute_register_example.cc [2]. UDF Example: https://github.com/apache/arrow/blob/master/cpp/examples/arrow/udf_example.cc [3] Expose JoinOptions(a): https://github.com/apache/arrow/blob/86915807af6fe10f44bc881e57b2f425f97c56c7/python/pyarrow/includes/libarrow.pxd#L1999 [4] Expose JoinOptions(b): https://github.com/apache/arrow/blob/86915807af6fe10f44bc881e57b2f425f97c56c7/python/pyarrow/_compute.pyx#L998 [5] Expose JoinType: https://github.com/apache/arrow/blob/86915807af6fe10f44bc881e57b2f425f97c56c7/python/pyarrow/includes/libarrow.pxd#L2473 [6] Expose HashJoinNodeOptions: https://github.com/apache/arrow/blob/86915807af6fe10f44bc881e57b2f425f97c56c7/python/pyarrow/includes/libarrow.pxd#L2504 [7] Expose the Join operator in Cython: https://github.com/apache/arrow/blob/86915807af6fe10f44bc881e57b2f425f97c56c7/python/pyarrow/_exec_plan.pyx#L167 [8] Join Usage in Table: https://arrow.apache.org/docs/python/generated/pyarrow.Table.html#pyarrow.Table.join [9] UDF tests: https://github.com/apache/arrow/blob/master/python/pyarrow/tests/test_udf.py [10] UDF Registration: https://github.com/apache/arrow/blob/86915807af6fe10f44bc881e57b2f425f97c56c7/python/pyarrow/_compute.pyx#L2504 Best, Vibhatha On Fri, Jun 24, 2022 at 3:29 AM Aldrin <akmon...@ucsc.edu.invalid> wrote: > Hi Mura, > > The short answer is: yes, it is possible. Naively, to expose such a > function something may need to be added in cython. I am learning more about > how to add new compute functions, so I am not sure yet if functions in the > function registry are automatically exposed to other languages (e.g. R, > python, etc.). When I find out more about how this is done, I can follow up > if this is still unanswered. > > There are examples of functions that you can call directly without using > "CallFunction;" for example, arrow::compute::Add. The second code sample on > [1] should show how this is done. > > [1]: https://arrow.apache.org/docs/cpp/compute.html#invoking-functions > > Aldrin Montana > Computer Science PhD Student > UC Santa Cruz > > > On Wed, Jun 22, 2022 at 12:34 PM Murali S <muralibala8...@gmail.com> > wrote: > > > Hi , > > > > I was wondering if it is possible to add a C++ Function to the Compute > > FunctionRegistry > > < > > > https://arrow.apache.org/docs/cpp/api/compute.html#_CPPv4N5arrow7compute16FunctionRegistryE > > > > > and > > then use the functions in python. Would be great if you could provide > > examples of such usage. > > Also are all functions added to the FunctionRegistry only callable using > > the GetFunction API with the function name as string ? Would like to know > > if there is a way to just do arrow::compute::FuncA where FuncA is the > newly > > added function > > > > Thanks in advance > > Mura > > >
