How to merge two dictionaries in Python? (code example)

Dictionaries can be merged in various ways by using various functions and constructors in Python. The following article will introduce to you how to use the update() method or ** to merge dictionaries. I hope it will be helpful to you.

Method 1: Use the update() method

By using the update() method in Python , which merges one list into another; it does not create a new list and returns None. [Video tutorial recommendation: Python3 tutorial]

Let’s look at the use of the update() method through a simple example.

# 使用update（）方法合并dict1和dict2
def Merge(dict1, dict2): 
    return(dict2.update(dict1)) 
dict1 = {'a': 10, 'b': 8} 
dict2 = {'d': 6, 'c': 4} 

# 输出Merge()函数的值
print(Merge(dict1, dict2)) 
print("\n")

# 输出dict1的值
print(dict1)
print("\n")

# 输出dict2的值
print(dict2)

Description: The dict1 list will be merged into the dict2 list.

Output:

Method 2: Use **

in Python Using ** is generally considered a trick in Python that can be used to merge two dictionaries and store them in a third dictionary, which does not affect the other two dictionaries.

Basic sentence pattern:

z = {**x, **y}

Explanation:

Use ** before a parameter to indicate that the parameter is a dictionary ;** [double star] is a shortcut that allows us to pass multiple arguments directly to a function using a dictionary.

The principle of using ** to merge two dictionaries: we first pass all the elements of the first dictionary to the third dictionary; then pass the second dictionary to the third dictionary, at this time Replace the duplicate keys of the first dictionary.

Let’s take a look at the use of (**) through a simple example.

def Merge(dict1, dict2): 
    res = {**dict1, **dict2} 
    return res 
      
dict1 = {'a': 10, 'b': 8} 
dict2 = {'d': 6, 'c': 4} 
dict3 = Merge(dict1, dict2) 
print("\n") 
print(dict1) 
print("\n") 
print(dict2) 
print("\n") 
print(dict3)

Output:

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