cast datetime[ms] to datetime[ns] in polars
Question:
I’d like to cast a column with the type datetype[ms] to datetime[ns] in polars. Is there a easy way to do this? I think there’s a problem with group_by_dynamic when using datetime[ms] and I’d like to test this
Answers:
s = pl.date_range(
datetime(2021, 1, 1), datetime(2021, 1, 2),
interval="3h", time_unit="ns"
)
# divide by 1 million is from ns to ms
(s.cast(int) // 1_000_000).cast(pl.Datetime).dt.cast_time_unit("ms")
shape: (9,)
Series: '' [datetime[ms]]
[
2021-01-01 00:00:00
2021-01-01 03:00:00
2021-01-01 06:00:00
2021-01-01 09:00:00
2021-01-01 12:00:00
2021-01-01 15:00:00
2021-01-01 18:00:00
2021-01-01 21:00:00
2021-01-02 00:00:00
]
I’d like to cast a column with the type datetype[ms] to datetime[ns] in polars. Is there a easy way to do this? I think there’s a problem with group_by_dynamic when using datetime[ms] and I’d like to test this
s = pl.date_range(
datetime(2021, 1, 1), datetime(2021, 1, 2),
interval="3h", time_unit="ns"
)
# divide by 1 million is from ns to ms
(s.cast(int) // 1_000_000).cast(pl.Datetime).dt.cast_time_unit("ms")
shape: (9,)
Series: '' [datetime[ms]]
[
2021-01-01 00:00:00
2021-01-01 03:00:00
2021-01-01 06:00:00
2021-01-01 09:00:00
2021-01-01 12:00:00
2021-01-01 15:00:00
2021-01-01 18:00:00
2021-01-01 21:00:00
2021-01-02 00:00:00
]