Tags¶

Tags are (short) strings that can be attached to individual days through calendar changes. They are useful for grouping related days into custom categories.

Adding tags¶

Tags are set via the tags field of a DayChange:

import exchange_calendars as ec
import exchange_calendars_extensions as ecx
from exchange_calendars_extensions.changes import (
    DayChange,
)

ecx.apply_extensions()

changeset = {
    "2022-12-27": DayChange(tags={"foo", "bar"}),
    "2022-12-28": DayChange(tags={"foo", "foobar"}),
}

ecx.change_calendar("XLON", changeset)

calendar = ec.get_calendar("XLON")

print(calendar.tags(return_tags=True))

Output:

2022-12-27       {foo, bar}
2022-12-28    {foo, foobar}
dtype: object

Like other holiday calendars, the tags(...) method returns a pandas.DatetimeIndex when return_tags=False (the default) or a pandas.Series when return_tags=True.

Filtering by date range and tags¶

Use start, end, and tags arguments to filter the results:

import pandas as pd
import exchange_calendars as ec
import exchange_calendars_extensions as ecx
from exchange_calendars_extensions.changes import (
    DayChange,
)

ecx.apply_extensions()

changeset = {
    "2022-12-27": DayChange(tags={"foo", "bar"}),
    "2022-12-28": DayChange(tags={"foo", "foobar"}),
}

ecx.change_calendar("XLON", changeset)

calendar = ec.get_calendar("XLON")

print(calendar.tags(start=pd.Timestamp("2022-12-28"), return_tags=True))
print("\n")
print(calendar.tags(end=pd.Timestamp("2022-12-27"), return_tags=True))
print("\n")
print(calendar.tags(tags={"foo"}, return_tags=True))

Output:

2022-12-28    {foo, foobar}
dtype: object

2022-12-27    {bar, foo}
dtype: object

2022-12-27       {bar, foo}
2022-12-28    {foo, foobar}
dtype: object

Note

When the tags argument is provided, a day matches the filter only if all given tags are present on that day.