slices_vs_filters.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Just to get a random list of numbers
import random

id_list = range(1, 101)
find_list = random.sample(id_list, random.randint(1, len(id_list)))
find_list.sort()

def get_ids(offset, limit):
    if offset + limit <= len(id_list):
        return id_list[offset:offset + limit]
    elif offset <= len(id_list):
        return id_list[offset:]
    else:
        return []


def get_by_slices():
    offset = 0
    chunk_count = 0
    chunk_size = 10

    while True:
        results = get_ids(offset, chunk_size)
        offset += chunk_size
        chunk_count += 1

        if not results:
            break;

        print "%" * 20
        print "Start Chunk: %s" % chunk_count
        print "%" * 20
        for result in results:
            if result in find_list:
                print result


def get_ids_improved(filters={}):
    numbers = filters.get('numbers')

    if numbers:
        return [ number for number in id_list if number in numbers ]

    return id_list


if __name__ == '__main__':
    print "We're looking for these numbers: ", find_list
    print
    print "%" * 50
    print "Example 1: How you would think getting slices by"
    print "an offset and limit would work"
    print "%" * 50
    get_by_slices()

    print
    print "%" * 50
    print "Example 2: Amazon's API's typically provide"
    print "an optional filters argument like this"
    print "%" * 50
    print get_ids_improved(filters={ "numbers": find_list })

    print
    print "%" * 50
    print "Same as above with no filter returns everything"
    print "%" * 50
    print get_ids_improved()