Output a log message every x% of a long computation

import logging

logging.basicConfig(level=logging.INFO)


def time_to_log(data, percent=10):
    percent = percent if percent > 1 else percent * 100
    data_size = len(data)
    log_every = data_size * percent / 100
    return float(data_size), lambda i: not i % log_every


data = range(100)
data_size, is_time_to_log = time_to_log(data, 0.2)

for i, d in enumerate(data):
    if is_time_to_log(i):
        logging.info("processing... {:.2%}".format(i / data_size))
    pass  # do whatever is needed
logging.info("processing... 100.00%")