from __future__ import absolute_import import random def smart_choice

from __future__ import absolute_import
import random

def smart_choice(items):
    """
    Select random item from items counting their weights.

    items is mapping a --> b:
     * a: real item value
     * b: item weight
    """

    total_weight = sum(items.itervalues())

    rnd = random.randint(1, total_weight)

    weight = 0
    for key, value in items.iteritems():
        weight += value
        if weight >= rnd:
            return key