What is the difference between dict.items() and dict.iteritems() in Python2?

Question

Are there any applicable differences between dict.items() and dict.iteritems()?

From the Python docs:

dict.items(): Return a

Answer 1

dict.items() return list of tuples, and dict.iteritems() return iterator object of tuple in dictionary as (key,value). The tuples are the same, but container is different.

dict.items() basically copies all dictionary into list. Try using following code to compare the execution times of the dict.items() and dict.iteritems(). You will see the difference.

import timeit

d = {i:i*2 for i in xrange(10000000)}  
start = timeit.default_timer() #more memory intensive
for key,value in d.items():
    tmp = key + value #do something like print
t1 = timeit.default_timer() - start

start = timeit.default_timer()
for key,value in d.iteritems(): #less memory intensive
    tmp = key + value
t2 = timeit.default_timer() - start

Output in my machine:

Time with d.items(): 9.04773592949
Time with d.iteritems(): 2.17707300186

This clearly shows that dictionary.iteritems() is much more efficient.