How do I filter a table by time of day across all dates?

I have a table with a timestamp column that spans multiple dates. I want to filter rows to only include times between 2:00 PM and 4:00 PM ET, regardless of the date.

Use the hourOfDay function to extract the hour component from your timestamp, then filter based on the hour value:

from deephaven import empty_table
from deephaven.time import to_j_time_zone, to_j_instant

et = to_j_time_zone("ET")
start_time = to_j_instant("2024-01-15T13:00:00 ET")

# Sample table with various timestamps across different dates
t = empty_table(10).update(
    [
        "Timestamp = start_time + i * 30 * MINUTE",
    ]
)

# Filter for times between 2:00 PM and 4:00 PM ET
result = t.where(
    "hourOfDay(Timestamp, et, false) >= 14 && hourOfDay(Timestamp, et, false) < 16"
)

This approach works by:

  1. Using hourOfDay(Timestamp, et, false) to extract the hour (0-23) from the timestamp in ET timezone.
  2. Filtering for hours between 14 (2:00 PM) and 15 (3:00 PM, up to but not including 4:00 PM).
  3. The condition checks that the hour is greater than or equal to 14 and less than 16, ensuring times from 2:00:00 PM through 3:59:59 PM are included.

Filtering with minutes

If you need more precise time filtering (e.g., 2:30 PM to 4:15 PM), combine hourOfDay and minuteOfHour:

start_time2 = to_j_instant("2024-01-15T14:15:00 ET")

t2 = empty_table(10).update(
    [
        "Timestamp = start_time2 + i * 15 * MINUTE",
    ]
)

# Filter for times between 2:30 PM and 4:15 PM ET
result2 = t2.where(
    "(hourOfDay(Timestamp, et, false) == 14 && minuteOfHour(Timestamp, et) >= 30) || "
    + "(hourOfDay(Timestamp, et, false) == 15) || "
    + "(hourOfDay(Timestamp, et, false) == 16 && minuteOfHour(Timestamp, et) <= 15)"
)

This filter includes:

  • Hour 14 (2:00 PM) with minutes greater than or equal to 30
  • All of hour 15 (3:00 PM)
  • Hour 16 (4:00 PM) with minutes less than or equal to 15

Note

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