polars.Series.dt.round#

Series.dt.round( every: str | dt.timedelta, offset: str | dt.timedelta | None = None, ) → Series[source]#

Divide the date/ datetime range into buckets.

Each date/datetime in the first half of the interval is mapped to the start of its bucket. Each date/datetime in the second half of the interval is mapped to the end of its bucket.

The every and offset argument are created with the the following string language:

1ns # 1 nanosecond
1us # 1 microsecond
1ms # 1 millisecond
1s # 1 second
1m # 1 minute
1h # 1 hour
1d # 1 calendar day
1w # 1 calendar week
1mo # 1 calendar month
1q # 1 calendar quarter
1y # 1 calendar year

These strings can be combined:

3d12h4m25s # 3 days, 12 hours, 4 minutes, and 25 seconds

Suffix with “_saturating” to indicate that dates too large for their month should saturate at the largest date (e.g. 2022-02-29 -> 2022-02-28) instead of erroring.

By “calendar day”, we mean the corresponding time on the next day (which may not be 24 hours, due to daylight savings). Similarly for “calendar week”, “calendar month”, “calendar quarter”, and “calendar year”.

Parameters:

every: Every interval start and period length
offset: Offset the window

Returns:

Series: Series of data type Date or Datetime.

Warning

This functionality is currently experimental and may change without it being considered a breaking change.

Examples

>>> from datetime import timedelta, datetime
>>> start = datetime(2001, 1, 1)
>>> stop = datetime(2001, 1, 2)
>>> s = pl.date_range(start, stop, timedelta(minutes=165), eager=True)
>>> s
shape: (9,)
Series: 'date' [datetime[μs]]
[
    2001-01-01 00:00:00
    2001-01-01 02:45:00
    2001-01-01 05:30:00
    2001-01-01 08:15:00
    2001-01-01 11:00:00
    2001-01-01 13:45:00
    2001-01-01 16:30:00
    2001-01-01 19:15:00
    2001-01-01 22:00:00
]
>>> s.dt.round("1h")
shape: (9,)
Series: 'date' [datetime[μs]]
[
    2001-01-01 00:00:00
    2001-01-01 03:00:00
    2001-01-01 06:00:00
    2001-01-01 08:00:00
    2001-01-01 11:00:00
    2001-01-01 14:00:00
    2001-01-01 17:00:00
    2001-01-01 19:00:00
    2001-01-01 22:00:00
]
>>> s.dt.round("1h").series_equal(s.dt.round(timedelta(hours=1)))
True

>>> start = datetime(2001, 1, 1)
>>> stop = datetime(2001, 1, 1, 1)
>>> s = pl.date_range(start, stop, "10m", eager=True)
>>> s.dt.round("30m")
shape: (7,)
Series: 'date' [datetime[μs]]
[
        2001-01-01 00:00:00
        2001-01-01 00:00:00
        2001-01-01 00:30:00
        2001-01-01 00:30:00
        2001-01-01 00:30:00
        2001-01-01 01:00:00
        2001-01-01 01:00:00
]