read_csv_converters.py

import pandas as pd


def double_number(x):
    """ Double a passed float
    :param x: Float that will be doubled.
    :return: A doubled float.
    """
    return float(x) * 2


if __name__ == '__main__':
    # Apply a converter to column 1.
    df = pd.read_csv('test.csv', header=0, converters={'col1': double_number})