How to merge two dictionaries (dict) in Python

This article mainly introduces how to merge two dictionaries (dict) in Python. it is a very practical technique in Python programming, for more information about how to merge two dictionaries (dict) in Python, see the following example. The specific method is as follows:

Two existing dictionaries, dict, are as follows:

dict1={1:[1,11,111],2:[2,22,222]}dict2={3:[3,33,333],4:[4,44,444]}

Merge the two dictionaries to get a similar result:

{1:[1,11,111],2:[2,22,222],3:[3,33,333],4:[4,44,444]}

Method 1:

dictMerged1=dict(dict1.items()+dict2.items())

Method 2:

dictMerged2=dict(dict1, **dict2)

Method 2 is equivalent:

dictMerged=dict1.copy()dictMerged.update(dict2)

Or:

dictMerged=dict(dict1)dictMerged.update(dict2)

Method 2 is much faster than method 1. the timeit test is as follows:

$ python -m timeit -s 'dict1=dict2=dict((i,i) for i in range(100))' 'dictMerged1=dict(dict1.items()+dict2.items())'  10000 loops, best of 3: 20.7 usec per loop$ python -m timeit -s 'dict1=dict2=dict((i,i) for i in range(100))' 'dictMerged2=dict(dict1,**dict2)'  100000 loops, best of 3: 6.94 usec per loop$ python -m timeit -s 'dict1=dict2=dict((i,i) for i in range(100))' 'dictMerged3=dict(dict1)' 'dictMerged3.update(dict2)'  100000 loops, best of 3: 7.09 usec per loop$ python -m timeit -s 'dict1=dict2=dict((i,i) for i in range(100))' 'dictMerged4=dict1.copy()' 'dictMerged4.update(dict2)'  100000 loops, best of 3: 6.73 usec per loop

I hope this article will help you with Python programming.