The simplest way to merge two dictionaries in python is by using the unpack operator(**). By applying the "**" operator to the dictionary, it expands its content being the collection of key-value pairs.,We can combine two dictionaries in python using dictionary comprehension. Here, we also use the for loop to iterate through the dictionary items and merge them to get the final output. If both the dictionaries have common keys, then the final output using this method will contain the value of the second dictionary. Check out the below example for a better understanding.,Unpacking the second dictionary using the "**" operator will help you merge two dictionaries and get your final output. However, this method is not highly used and recommended because it will only work if the keys of the second dictionary are compulsorily strings. If any int value is encountered, then it will raise the "TypeError" method.,As dictionary is also iterable, we can use the chain() function from itertools class and merge two dictionaries. The return type of this method will be an object, and hence, we can convert the dictionary using the dict() constructor.
sample_dict = {
"Language_1": "Python",
"Langauge_2": "C++",
"Language_3": "Java"
}
print(sample_dict){
'Language_1': 'Python',
'Langauge_2': 'C++',
'Language_3': 'Java'
}dict_1 = {
'John': 15,
'Rick': 10,
'Misa': 12
}
dict_2 = {
'Bonnie': 18,
'Rick': 20,
'Matt': 16
}
dict_1.update(dict_2)
print('Updated dictionary:')
print(dict_1){
'John': 15,
'Rick': 20,
'Misa': 12,
'Bonnie': 18,
'Matt': 16
}def Merge(dict_1, dict_2):
result = dict_1 | dict_2
return result
# Driver code
dict_1 = {
'John': 15,
'Rick': 10,
'Misa': 12
}
dict_2 = {
'Bonnie': 18,
'Rick': 20,
'Matt': 16
}
dict_3 = Merge(dict_1, dict_2)
print(dict_3)dict_1 = {
'John': 15,
'Rick': 10,
'Misa': 12
}
print(dict( ** dict_1))Instead of iterating over every dictionary, how about reverse mylist and iteratively update an output dictionary? Then every key-value pair inserted into out from the back will be updated from the front if a key already exists.
out = {}
for d in mylist[::-1]:
out.update(d)Output:
{
'b': 3,
'A': 8,
'Z': 2,
'V': 1
}Use the appropriate operator, you can't use |= with a tuple
def concatenate_dict(dict_list: list) - > dict:
final_dict = {}
for d in dict_list:
for k, v in d.items():
if k not in final_dict:
final_dict[k] = v
return final_dictIterate on the dicts backwards and use dict.update
def concatenate_dict(dict_list: list) - > dict:
final_dict = {}
for d in reversed(dict_list):
final_dict.update(d)
return final_dictCould be with reduce and merge operator
from functools
import reduce
def concatenate_dict(dict_list: list) - > dict:
return reduce(lambda x, y: x | y, reversed(dict_list))However, I'd like to highlight method dict.setdefault, which does exactly what you want: add a key: value to a dict, only if the key wasn't already in the dict.
def concatenate_dict(dict_list: list) - > dict:
final_dict = {}
for d in dict_list:
for k, v in d.items():
final_dict.setdefault(k, v)
return final_dict
mylist = [{
'b': 7
}, {
'b': 10,
'A': 8,
'Z': 2,
'V': 1
}]
print(concatenate_dict(mylist))
# {
'b': 7,
'A': 8,
'Z': 2,
'V': 1
}November 18, 2021February 22, 2022
Let’s see what this looks like in Python:
# Merge two Python dictionaries using the merge operator in Python 3.9 +
dict1 = {
'a': 1,
'b': 2
}
dict2 = {
'c': 3,
'd': 4
}
dict3 = dict1 | dict2
print(dict3)
# Returns: {
'a': 1,
'b': 2,
'c': 3,
'd': 4
}Let’s see what this looks like:
# Merge two Python dictionaries using the merge operator in Python 3.9 +
dict1 = {
'a': 1,
'b': 2
}
dict2 = {
'c': 3,
'd': 4
}
dict1 |= dict2
print(dict1)
# Returns: {
'a': 1,
'b': 2,
'c': 3,
'd': 4
}Now let’s take a look at an example of what happens when two dictionaries have a shared key.
# Merge two Python dictionaries using the merge operator in Python 3.9 +
dict1 = {
'a': 1,
'b': 2
}
dict2 = {
'c': 3,
'a': 4
}
dict3 = dict1 | dict2
print(dict3)
# Returns: {
'a': 4,
'b': 2,
'c': 3
}What happens, though, if your dictionaries share keys? Let’s take a look at what happens:
# Merge two Python dictionaries using item unpacking
dict1 = {
'a': 1,
'b': 2
}
dict2 = {
'c': 3,
'a': 4
}
dict3 = {
** dict1,
** dict2
}
print(dict3)
# Returns: {
'a': 4,
'b': 2,
'c': 3
}Let’s see how this works when all the keys are unique:
# Merge two Python dictionaries using.update()
dict1 = {
'a': 1,
'b': 2
}
dict2 = {
'c': 3,
'd': 4
}
dict3 = dict1.copy()
dict3.update(dict2)
print(dict3)
# Returns: {
'a': 1,
'b': 2,
'c': 3,
'd': 4
}We learned a way to all contents of a dictionary to another dictionary without overwriting the values of similar keys.,In this article, we will discuss how to add the contents of a dictionary to another dictionary without overwriting values of similar keys.,28. Python – Dictionary Add,30. Python – Dictionary Print
Suppose we have two dictionaries with some similar keys. Like this,
dict_1 = {
"Hello": 56,
"at": 23,
"test": 43,
"this": 12
}
dict_2 = {
'test': 4,
'at': 5,
'why': 6,
'Hello': 20
}dict_1 and dict_2 have following common keys – ‘test’, ‘at’, ‘Hello’. Now we want to add the contents of a dictionary dict_2 to dictionary dict_1. But instead of overwriting values for common keys, we want to merge the values of common keys while adding. For example, after adding the contents of dict_2 to dict_1, the final content of dict_1 should be like this,
{
'Hello': [56, 20],
'at': [23, 5],
'test': [43, 4],
'this': 12,
'why': 6
}Let’s understand by an example,
dict_1 = {
"Hello": 56,
"at": 23,
"test": 43,
"this": 12
}
dict_2 = {
'test': 4,
'at': 5,
'why': 6,
'Hello': 20
}
for key, value in dict_2.items():
if key in dict_1:
if isinstance(dict_1[key], list):
dict_1[key].append(value)
else:
temp_list = [dict_1[key]]
temp_list.append(value)
dict_1[key] = temp_list
else:
dict_1[key] = value
print(dict_1)I have two dictionaries and I want to anycodings_python combine them. ,Note that the recursion only works for anycodings_python values that are dictionaries. For anycodings_python example:,You could use collections.defaultdict anycodings_python with a dict.,Usage of progressHandler with PHContentEditingInputRequestOptions
I have two dictionaries and I want to anycodings_python combine them.
dict1 = {
'abc': {
'test1': 123
}
}
dict2 = {
'abc': {
'test2': 456
}
}I want to end up with
{
'abc': {
'test1': 123,
'test2': 456
}
}if dict2 = {'abc': 100} then I would want:
{
'abc'
100
}IIUC, you could do the following:
def recursive_update(d1, d2):
""
"Updates recursively the dictionary values of d1"
""
for key, value in d2.items():
if key in d1 and isinstance(d1[key], dict) and isinstance(value, dict):
recursive_update(d1[key], value)
else:
d1[key] = value
dict1 = {
'abc': {
'test1': 123
}
}
dict2 = {
'abc': {
'test2': 456
}
}
recursive_update(dict1, dict2)
print(dict1)Output
{
'abc': {
'test1': 123,
'test2': 456
}
}Note that the recursion only works for anycodings_python values that are dictionaries. For anycodings_python example:
dict1 = {
'abc': {
'test1': 123
}
}
dict2 = {
'abc': 100
}You have a dictionary in a dictionary anycodings_python und you want to update the inner anycodings_python dictionary with the inner dictionary of anycodings_python the other one. So you have to apply the anycodings_python update method to the inner dictionary:
dict1["abc"].update(dict2["abc"])You could use collections.defaultdict anycodings_python with a dict.
from collections
import defaultdict
merge = defaultdict(dict)
# Handle nesting
for d in [dict1, dict2]:
for k0, v0 in d.items():
for k1, v1 in v0.items():
merge[k0][k1] = v1 # Assign to defaultdict
print(dict(merge)) # - > {
'abc': {
'test1': 123,
'test2': 456
}
}Or you could use dict.setdefault.
merge = {}
for d in [dict1, dict2]:
for k0, v0 in d.items():
merge.setdefault(k0, {})
for k1, v1 in v0.items():
merge[k0][k1] = v1
print(merge) # - > {
'abc': {
'test1': 123,
'test2': 456
}
}