parameterize_values

Expands a single function into n, each of which corresponds to a function in which the parameter value is replaced by that specific value.

import pandas as pd
from hamilton.function_modifiers import parameterize_values
import internal_package_with_logic

ONE_OFF_DATES = {
     #output name        # doc string               # input value to function
    ('D_ELECTION_2016', 'US Election 2016 Dummy'): '2016-11-12',
    ('SOME_OUTPUT_NAME', 'Doc string for this thing'): 'value to pass to function',
}
            # parameter matches the name of the argument in the function below
@parameterize_values(parameter='one_off_date', assigned_output=ONE_OFF_DATES)
def create_one_off_dates(date_index: pd.Series, one_off_date: str) -> pd.Series:
    """Given a date index, produces a series where a 1 is placed at the date index that would contain that event."""
    one_off_dates = internal_package_with_logic.get_business_week(one_off_date)
    return internal_package_with_logic.bool_to_int(date_index.isin([one_off_dates]))

We see here that parameterize allows you keep your code DRY by reusing the same function to create multiple distinct outputs. The parameter key word argument has to match one of the arguments in the function. The rest of the arguments are pulled from outside the DAG. The _assigned_output_ key word argument takes in a dictionary of tuple(Output Name, Documentation string) -> value.

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Reference Documentation

class hamilton.function_modifiers.parameterize_values(parameter: str, assigned_output: Dict[Tuple[str, str], Any])

Expands a single function into n, each of which corresponds to a function in which the parameter value is replaced by that specific value.

import pandas as pd
from hamilton.function_modifiers import parameterize_values
import internal_package_with_logic

ONE_OFF_DATES = {
     #output name        # doc string               # input value to function
    ('D_ELECTION_2016', 'US Election 2016 Dummy'): '2016-11-12',
    ('SOME_OUTPUT_NAME', 'Doc string for this thing'): 'value to pass to function',
}
            # parameter matches the name of the argument in the function below
@parameterize_values(parameter='one_off_date', assigned_output=ONE_OFF_DATES)
def create_one_off_dates(date_index: pd.Series, one_off_date: str) -> pd.Series:
    '''Given a date index, produces a series where a 1 is placed at the date index that would contain that event.'''
    one_off_dates = internal_package_with_logic.get_business_week(one_off_date)
    return internal_package_with_logic.bool_to_int(date_index.isin([one_off_dates]))

__init__(parameter: str, assigned_output: Dict[Tuple[str, str], Any])

Constructor for a modifier that expands a single function into n, each of which corresponds to a function in which the parameter value is replaced by that specific value.

Parameters:

• parameter – Parameter to expand on.

• assigned_output – A map of tuple of [parameter names, documentation] to values

Note: this was previously called @parametrized.