David - Thanks for the pointers. I didn't know you could cast a timestamp to time type to extract the hour/minute information. Nice!
Rok - Not sure I understand what you mean... My input is UTC but I want to extract the time information local to New York Timezone (e.g. filter time to 10 AM New York time). How would I do this without assume_timezone? On Thu, Feb 3, 2022 at 10:13 AM Rok Mihevc <rok.mih...@gmail.com> wrote: > Hey Li, > > If your input data is in UTC you don't need assume_timezone [1]. You > would need it if your input was America/New_York local time and you > wanted to convert to a zoned timestamp array where underlying data is > in UTC and timezone is metadata only. Perhaps python tests are > interesting for reference [2]. > > Available extraction kernels are listed here: [3]. > > Rok > > [1] > https://arrow.apache.org/docs/python/generated/pyarrow.compute.assume_timezone.html > [2] > https://github.com/apache/arrow/blob/master/python/pyarrow/tests/test_compute.py#L1908-L1999 > [3] > https://arrow.apache.org/docs/cpp/compute.html#temporal-component-extraction > > On Thu, Feb 3, 2022 at 3:54 PM Li Jin <ice.xell...@gmail.com> wrote: > > > > Hello! > > > > I am new to the Arrow C++ compute engine and trying to figure out this > time > > zone conversion and time extraction: > > > > t.dt.tz_convert('America/New_York').dt.time == datetime.time(11, 30, 0) > > > > So I started looking at: > > > https://github.com/apache/arrow/blob/master/cpp/src/arrow/compute/kernels/scalar_temporal_unary.cc > > > > and found these these functions seem relevant: > > assume_timezone > > hour > > minute > > > > So my thinking is trying to figure out a way to build plan that basically > > does these steps: > > (1) Assume timezone to New_York (input data is UTC) > > (2) Extract hour value > > (3) Extract minute value > > (4) Filter on hour and minute value > > > > I wonder what is a good way to map these functions in > > scalar_temporal_unary to an ExecPlan? (Looked under > > https://github.com/apache/arrow/tree/master/cpp/src/arrow/compute/exec > but > > didn't see anything obvious) > > > > Thanks! > > Li >
