pyramid

pyramid.py

import sys
import logging
import itertools

logging.basicConfig(format="%(asctime)s %(message)s", level=logging.DEBUG)
def termGenerator(sequence, start, length, k):
    """Generate kth term in a rolling sequence of 1, 3, 5... letters
    Even terms are reversed
    """
    # pick seqLen chars after skipping first startPos chars
    # logging.debug("Picking %d letters after %d", termLen, startPos)
    chars = itertools.islice(itertools.cycle(sequence), start, start + length)
    term = "".join(chars)
    if k % 2 == 0:
        term = term[::-1]
    return term

termLen = lambda k: 1 + (k - 1)* 2
startPos = lambda k: (k-1)** 2
def main(sequence, depth, direction):
    """TODO: Docstring for main.
    :returns: TODO

    """
    logging.debug("seq %s depth %s dir %s", sequence, depth, direction)

    # terms  1, 3, 5, 7, 9 .... 
    start = 1
    end = depth
    if direction == -1:
        start = end
        end = 0

    skip =0
    pos = 1
    for i in range(start, end, direction):
        term = termGenerator(sequence, skip, termLen(i), pos)
        pos +=1 
        skip += len(term)
        print(term)


if __name__ == "__main__":
    seq, depth, direction = sys.argv[1:]
    main("abc", 6, 1)
    main("1234567890", 10, -1)