How can I use a backend's built-in function to create a new column in an Ibis dataframe?

[stereoF]

I have constructed an Ibis dataframe that includes a column named account_id. I would like to hash and modulo this column and assign the result to a new column. I am using ClickHouse as the backend, which has the halfMD5 function.

[gforsyth]

Hey @stereoF -- you can use a builtin UDF for this:

[ins] In [1]: import ibis

[ins] In [2]: con = ibis.clickhouse.connect()

[ins] In [3]: ibis.options.interactive = True

[ins] In [4]: ibis.set_backend(con)

[ins] In [5]: t = ibis.memtable({"b": ["hey", "yo"]})

[ins] In [6]: t
Out[6]: 
┏━━━━━━━━┓
┃ b      ┃
┡━━━━━━━━┩
│ string │
├────────┤
│ hey    │
│ yo     │
└────────┘

[ins] In [7]: @ibis.udf.scalar.builtin
         ...: def halfMD5(val) -> int: ...

[ins] In [8]: t.mutate(c=halfMD5(t.b))
Out[8]: 
┏━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━┓
┃ b      ┃ c                   ┃
┡━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━┩
│ string │ int64               │
├────────┼─────────────────────┤
│ hey    │ 6942282591847239551 │
│ yo     │ 7854286431059639165 │
└────────┴─────────────────────┘