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

# # Python performance optimization

# ## Membership testing is faster in dict than in list. 
# 
# Python dictionaries use hash tables, this means that a lookup operation (e.g., if x in y) is O(1). A lookup operation in a list means that the entire list needs to be iterated, resulting in O(n) for a list of length n. http://www.clips.ua.ac.be/tutorials/python-performance-optimization

# In[1]:


import timeit
def test_ifin(d):
    if 5000 in d:
        a = 1
    else:
        a = 2

d1 = dict.fromkeys(range(10000), True)
d2 = range(10000)


# In[2]:


print (timeit.timeit(lambda: test_ifin(d1), number=1000))
print (timeit.timeit(lambda: test_ifin(d2), number=1000))


# In[ ]: