Artip – Scalar Temporal Period Identifiers for Power BI

Artip is a Python library that generates unique, scalar integer identifiers for temporal periods, optimized for storage and filtering in Power BI's Vertipaq engine.

Features

• Scalar Period IDs: Encode temporal periods as 64-bit integers for efficient Power BI representation
• Flexible Granularity: Support for year, month, day, hour, minute, and second-level periods
• Period Constraints: Optional maximum period size enforcement
• Calendar Generation: Automatic generation of periodic calendar tables for Power BI filtering
• Type-Safe: Full Python type hints for IDE integration and runtime checks
• No Global State: Thread-safe with all state encapsulated in Artip instances

Installation

pip install artip

Quick Start

from datetime import date
from artip import Artip

# Create an Artip instance
artip = Artip(
    min_time=date(2024, 1, 1),
    max_time=date(2024, 12, 31),
    granularity='day'
)

# Generate a period identifier
period_id = artip.make_period_id(
    start=date(2024, 1, 1),
    end=date(2024, 1, 31)
)
print(f"Period ID: {period_id}")  # Output: Period ID: 101

# Retrieve the time range for a period
start, end = artip.get_period_range(period_id)
print(f"Period range: {start} to {end}")

# Generate a calendar table for Power BI
calendar = artip.make_calendar_table()
print(calendar)

Use Cases

ETL Pipeline Integration

Use Artip in Python ETL pipelines to generate period identifiers for facts tables:

from datetime import date
import polars as pl
from artip import Artip

# Setup period encoding
artip = Artip(
    min_time=date(2020, 1, 1),
    max_time=date(2030, 12, 31),
    granularity='month'
)

# Process fact records
facts = pl.DataFrame({
    'transaction_date': [date(2024, 3, 15), date(2024, 5, 20)],
    'amount': [100.0, 250.0]
})

def add_period_id(record):
    return artip.make_period_id(record['transaction_date'], record['transaction_date'])

facts = facts.with_columns(
    period_id=facts['transaction_date'].map_elements(
        lambda d: artip.make_period_id(d, d).value
    )
)

Calendar Table for Power BI

Generate a calendar table to enable period-based filtering:

calendar_table = artip.make_calendar_table()

# Save to CSV for Power BI import
calendar_table.write_csv('period_calendar.csv')

API Reference

Artip Class

Constructor

Artip(
    min_time: Union[date, datetime],
    max_time: Union[date, datetime],
    granularity: str = 'day',
    period_max_size: Optional[int] = None
)

Parameters:

• min_time: Minimum time boundary (inclusive)
• max_time: Maximum time boundary (inclusive)
• granularity: Temporal granularity ('year', 'month', 'day', 'hour', 'minute', 'second')
• period_max_size: Maximum allowed period length in granularity units (None = unlimited)

Raises:

• InvalidIntervalError: If min_time >= max_time
• InvalidGranularityError: If granularity is not supported

make_period_id(start, end) -> PeriodId

Generate a unique identifier for a temporal period.

Parameters:

• start: Period start time (inclusive)
• end: Period end time (inclusive)

Returns: PeriodId object

Raises:

• InvalidIntervalError: If start > end or period outside bounds
• PeriodTooLargeError: If period exceeds period_max_size

get_period_range(period_id) -> Tuple[datetime, datetime]

Retrieve the time range for a period identifier.

Parameters:

• period_id: A PeriodId generated by this instance

Returns: Tuple of (start_time, end_time)

Raises:

• InvalidIntervalError: If period_id not generated by this instance

make_calendar_table() -> pl.DataFrame

Generate a periodic calendar table for Power BI filtering.

Returns: Polars DataFrame with columns:

• date: The timepoint at the specified granularity
• period_id: The PeriodId value (Int64)
• label: Relationship to period ('starts', 'ends', 'in')

PeriodId Class

Lightweight dataclass representing a period identifier.

Attributes:

• value: int – The encoded period identifier

Methods:

• __str__() – Returns string representation
• __eq__(other) – Equality comparison
• __hash__() – Hashable for use in sets/dicts

Exceptions

• ArtipError – Base exception
• InvalidIntervalError – Invalid time interval
• PeriodTooLargeError – Period exceeds constraints
• InvalidGranularityError – Unsupported granularity

Design Rationale

Artip encodes periods as composite integers:

PeriodId = (start_id) * 10^period_size + period_length

Where:

• start_id = offset from min_time in granularity units
• period_length = end_id - start_id
• period_size = number of digits allocated for period_length

This design ensures:

• Efficient storage in 64-bit integers
• Fast period range queries
• Compatible filtering in Power BI

Requirements

• Python 3.10+
• Polars 0.20.0+

License

MIT

Contributing

Contributions are welcome! Please ensure:

• All tests pass: pytest
• Code is type-checked: mypy
• Code adheres to style: ruff