convert_gdf_to_wkt.py

from geopandas import GeoDataFrame
from typing import Union
import pandas as pd

def geodf_to_wkt_csv(gdf: GeoDataFrame, output_file: Union[str, None] = None) -> pd.DataFrame:
    """
    Converts a GeoDataFrame's geometry column to WKT format and optionally saves it to a CSV file.

    Args:
        gdf (GeoDataFrame): The input GeoDataFrame to be converted.
        output_file (Union[str, None]): The file path to save the resulting CSV. If None, the file is not saved.

    Returns:
        pd.DataFrame: A pandas DataFrame with the geometry column converted to WKT.
    """
    # Convert the geometry column to WKT
    df = gdf.copy()
    df["geometry"] = df["geometry"].apply(lambda geom: geom.wkt)

    # Save to CSV if an output file is provided
    if output_file:
        df.to_csv(output_file, index=False)

    return df