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return a random item in a list, which has different probability.
# -*- coding: utf-8 -*-
# Reference: Python Cookbook 2nd Ed. p.188
import random
def random_pick(item_list, probabilities):
""" return a random item in a list, which has different probability.
item_list (list of item)
probabilities (list of float. prob. should be 0 <= x <= 1)
for p in probabilities:
if not isinstance(p, float):
raise TypeError("{0} is not float".format(p))
if p < 0.0 or 1.0 < p:
raise ValueError("{0} should be between 0.0 to 1.0".format(p))
x = random.uniform(0, 1)
cumulative_probability = 0.0
for item, item_prob in zip(item_list, probabilities):
cumulative_probability += item_prob
if x < cumulative_probability:
return item
if __name__ == '__main__':
item_list = ["aaa", "bbb", "ccc", "ddd", "eee"]
probabilities = [0.05, 0.1, 0.15, 0.3, 0.4]
results = {}
for i in range(1, NUM_ATTEMPTS):
print("Test #{0}".format(i))
picked_item = random_pick(item_list, probabilities)
results[picked_item] = results.setdefault(picked_item, 0) + 1
print("random pick result: {0}".format(picked_item))
print("## total result ##")
for item, count in results.iteritems():
print("{0}: {1} times".format(item, count))
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