arithmetic.py

#!/usr/bin/env python

# simple script to practice mental arithmetic

import random
import operator
import argparse
import re

answer_re = re.compile(r'^[-+]?\d+$')

ops = (
    ('+', operator.add),
    ('-', operator.sub),
    ('x', operator.mul),
)


def sample(x):
    """Sample generator."""

    while True:
        yield random.sample(x, 1)[0]


def main():
    """"""

    # set up argument parser
    parser = argparse.ArgumentParser()
    parser.add_argument('--series', help="Series to drill.", type=int, default=None)
    parser.add_argument('--min', help="Minimum multiplier.", type=int, default=2)
    parser.add_argument('--max', help="Maximum multiplier.", type=int, default=12)

    args = parser.parse_args()

    errors = 0

    try:
        n = 1
        for label, op in sample(ops):
            attempt = 1

            x = random.randint(args.min, args.max)
            y = args.series if args.series else random.randint(args.min, args.max)

            # flip arguments if drilling a particular series
            if args.series and random.random() < 0.5:
                x, y = y, x

            while True:
                answer = raw_input(
                    "{0}/{1}: {2:>2} {3} {4:>2} = ".format(n, attempt, x, label, y)
                )

                # check answer
                if answer_re.match(answer) and int(answer) == op(x, y):
                    print
                    break
                else:
                    errors += 1

                attempt += 1

            n += 1

    except KeyboardInterrupt:
        print "\n\nErrors: {0}".format(errors)

if __name__ == '__main__':
    main()