Source code for pm4py.statistics.traces.cycle_time.polars.get

'''
    PM4Py – A Process Mining Library for Python
Copyright (C) 2024 Process Intelligence Solutions UG (haftungsbeschränkt)

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program.  If not, see this software project's root or
visit <https://www.gnu.org/licenses/>.

Website: https://processintelligence.solutions
Contact: info@processintelligence.solutions
'''
from enum import Enum
from typing import Dict, Optional, Any, Union

import polars as pl

from pm4py.statistics.traces.cycle_time.util import compute
from pm4py.util import exec_utils, constants, xes_constants




class Parameters(Enum):
    TIMESTAMP_KEY = constants.PARAMETER_CONSTANT_TIMESTAMP_KEY
    START_TIMESTAMP_KEY = constants.PARAMETER_CONSTANT_START_TIMESTAMP_KEY
    CASE_ID_KEY = constants.PARAMETER_CONSTANT_CASEID_KEY





def apply(
    lf: pl.LazyFrame,
    parameters: Optional[Dict[Union[str, Parameters], Any]] = None,
) -> float:
    """
    Computes the cycle time starting from a Polars LazyFrame

    The definition that has been followed is the one proposed in:
    https://www.presentationeze.com/presentations/lean-manufacturing-just-in-time/lean-manufacturing-just-in-time-full-details/process-cycle-time-analysis/calculate-cycle-time/#:~:text=Cycle%20time%20%3D%20Average%20time%20between,is%2024%20minutes%20on%20average.

    So:
    Cycle time  = Average time between completion of units.

    Example taken from the website:
    Consider a manufacturing facility, which is producing 100 units of product per 40 hour week.
    The average throughput rate is 1 unit per 0.4 hours, which is one unit every 24 minutes.
    Therefore the cycle time is 24 minutes on average.

    Parameters
    ------------------
    lf
        LazyFrame
    parameters
        Parameters of the algorithm, including:
        - Parameters.START_TIMESTAMP_KEY => the attribute acting as start timestamp
        - Parameters.TIMESTAMP_KEY => the attribute acting as timestamp
        - Parameters.CASE_ID_KEY => the attribute acting as case identifier

    Returns
    ------------------
    cycle_time
        Cycle time
    """
    if parameters is None:
        parameters = {}

    timestamp_key = exec_utils.get_param_value(
        Parameters.TIMESTAMP_KEY,
        parameters,
        xes_constants.DEFAULT_TIMESTAMP_KEY,
    )
    start_timestamp_key = exec_utils.get_param_value(
        Parameters.START_TIMESTAMP_KEY, parameters, timestamp_key
    )
    case_id_key = exec_utils.get_param_value(
        Parameters.CASE_ID_KEY, parameters, constants.CASE_CONCEPT_NAME
    )

    # Handle case where start_timestamp_key and timestamp_key are the same
    if start_timestamp_key == timestamp_key:
        # Select unique columns and rename for clarity
        events_df = lf.select([
            pl.col(timestamp_key).alias("start_ts"),
            pl.col(timestamp_key).alias("end_ts"), 
            pl.col(case_id_key)
        ]).collect()
        start_col_name = "start_ts"
        end_col_name = "end_ts"
    else:
        # Select different timestamp columns
        events_df = lf.select([start_timestamp_key, timestamp_key, case_id_key]).collect()
        start_col_name = start_timestamp_key
        end_col_name = timestamp_key

    # Convert timestamps to events tuples
    events = []
    for row in events_df.iter_rows():
        start_idx = events_df.columns.index(start_col_name)
        end_idx = events_df.columns.index(end_col_name)

        start_ts = row[start_idx].timestamp() if hasattr(row[start_idx], 'timestamp') else row[start_idx]
        end_ts = row[end_idx].timestamp() if hasattr(row[end_idx], 'timestamp') else row[end_idx]
        events.append((start_ts, end_ts))

    # Get number of unique cases
    num_instances = events_df[case_id_key].n_unique()

    return compute.cycle_time(events, num_instances)