pydiverse-transform 0.7.1

Pipe based dataframe manipulation library that can also transform data on SQL databases

pydiverse.transform

Pipe based dataframe manipulation library that can also transform data on SQL databases

This is an early stage version 0.x, however, it is already used in real projects. We are happy to receive your feedback as issues on the GitHub repo. Feel free to also comment on existing issues to extend them to your needs or to add solution ideas.

Usage

pydiverse.transform can either be installed via pypi with pip install pydiverse-transform or via conda-forge with conda install pydiverse-transform -c conda-forge. Our recommendation would be to use pixi which is also based on conda-forge:

mkdir my_project
pixi init
pixi add pydiverse-transform

With pixi, you run python like this:

pixi run python -c 'import pydiverse.transform'

or this:

pixi run python my_script.py

Example

This code illustrates how to use pydiverse.transform with pandas and SQL:

from pydiverse.transform import Table
from pydiverse.transform.lazy import SQLTableImpl
from pydiverse.transform.eager import PandasTableImpl
from pydiverse.transform.core.verbs import *
import pandas as pd
import sqlalchemy as sqa


def main():
    dfA = pd.DataFrame(
        {
            "x": [1],
            "y": [2],
        }
    )
    dfB = pd.DataFrame(
        {
            "a": [2, 1, 0, 1],
            "x": [1, 1, 2, 2],
        }
    )

    input1 = Table(PandasTableImpl("dfA", dfA))
    input2 = Table(PandasTableImpl("dfB", dfB))

    transform = (
        input1
        >> left_join(input2 >> select(), input1.x == input2.x)
        >> mutate(x5=input1.x * 5, a=input2.a)
    )
    out1 = transform >> collect()
    print("\nPandas based result:")
    print(out1)

    engine = sqa.create_engine("sqlite:///:memory:")
    dfA.to_sql("dfA", engine, index=False, if_exists="replace")
    dfB.to_sql("dfB", engine, index=False, if_exists="replace")
    input1 = Table(SQLTableImpl(engine, "dfA"))
    input2 = Table(SQLTableImpl(engine, "dfB"))
    transform = (
        input1
        >> left_join(input2 >> select(), input1.x == input2.x)
        >> mutate(x5=input1.x * 5, a=input2.a)
    )
    out2 = transform >> collect()
    print("\nSQL query:")
    print(transform >> build_query())
    print("\nSQL based result:")
    print(out2)

    out1 = out1.sort_values("a").reset_index(drop=True)
    out2 = out2.sort_values("a").reset_index(drop=True)
    assert len(out1.compare(out2)) == 0


if __name__ == "__main__":
    main()