calgebra 0.9.1

A tiny DSL for calendar interval algebra - compose, filter, and query time ranges using set operations.

calgebra 🗓️

Set algebra for calendars. Compose lazily and query efficiently.

Installation

pip install calgebra

# Or with Google Calendar support
pip install calgebra[google-calendar]

# Or with iCalendar (.ics) file support
pip install calgebra[ical]

Quick Start

from calgebra import day_of_week, time_of_day, hours, at_tz, pprint, HOUR
from itertools import islice

# Setup
tz = "US/Pacific"
at = at_tz(tz)

# 1. Define Availability
weekdays = day_of_week(
    ["monday", "tuesday", "wednesday", "thursday", "friday"],
    tz=tz
)
work_hours = time_of_day(start=9*HOUR, duration=8*HOUR, tz=tz)
business_hours = weekdays & work_hours

# 2. Define Constraints
lunch = time_of_day(start=12*HOUR, duration=1*HOUR, tz=tz) 
monday_sync = day_of_week("monday", tz=tz) & time_of_day(start=9*HOUR, duration=1*HOUR, tz=tz)
busy = lunch | monday_sync

# 3. Calculate Free Time
free_time = (business_hours - busy) & (hours >= 2)

# 4. Query (Jan 2025)
start, end = at("2025-01-01"), at("2025-02-01")

print("Forward options:")
pprint(islice(free_time[start:end], 5), tz=tz)

print("\nReverse options (Last 3 in Jan):")
pprint(islice(free_time[end:start:-1], 3), tz=tz)

Intervals use exclusive end bounds ([start, end)), matching Python slicing. Interval(start=10, end=13) represents 3 seconds. Intervals are automatically clipped to query bounds.

Core Features:

• Set operations: | (union), & (intersection), - (difference), ~ (complement)
• Recurring patterns: recurring(), day_of_week(), time_of_day() (RFC 5545 via python-dateutil)
• Reverse iteration: timeline[end:start:-1] for reverse chronological order
• Aggregations: total_duration, max_duration, min_duration, count_intervals, coverage_ratio
• Transformations: buffer() (add time around intervals), merge_within() (coalesce nearby intervals)
• Google Calendar: calgebra.gcsa.calendars() for read/write operations
• iCalendar (.ics): Load/save timelines to standard RFC 5545 files

→ Quick-start | Tutorial | API Reference | Google Calendar

License

MIT License - see LICENSE file for details.