# Python >= 3.5:
def merge_dictionaries(a, b):
return {**a, **b}
# else:
def merge_dictionaries(a, b):
c = a.copy() # make a copy of a
c.update(b) # modify keys and values of a with the b ones
return c
a = { 'x': 1, 'y': 2}
b = { 'y': 3, 'z': 4}
print(merge_dictionaries(a, b)) # {'y': 3, 'x': 1, 'z': 4}
dict1 = {'color': 'blue', 'shape': 'square'}
dict2 = {'color': 'red', 'edges': 4}
dict1.update(dict2) #if a key exists in both, it takes the value of the second dict
# dict1 = {'color': 'red', 'shape': 'square', 'edges': 4}
# dict2 is left unchanged
# Python 3.9
z = x | y
# Python 3.5
z = {**x, **y}
# Python <= 3.4
def merge_two_dicts(x, y):
z = x.copy() # start with keys and values of x
z.update(y) # modifies z with keys and values of y
return z
z = merge_two_dicts(x, y)
# Example usage:
# Say you have the following dictionaries and want to merge dict_b into dict_a
dict_a = {"ABC": {"DE": {"F": "G"}}}
dict_b = {"ABC": {"DE": {"H": "I"}, "JKL": "M"}}
def merge_nested_dictionaries(dict_a, dict_b, path=None):
"""
recursive function for merging dict_b into dict_a
"""
if path is None:
path = []
for key in dict_b:
if key in dict_a:
if isinstance(dict_a[key], dict) and isinstance(dict_b[key], dict):
merge_nested_dictionaries(dict_a[key], dict_b[key], path + [str(key)])
# if the b dictionary matches the a dictionary from here on, skip adding it
elif dict_a[key] == dict_b[key]:
pass
# if the same series of keys lead to different terminal values in
# each dictionary, the dictionaries can't be merged unambiguously
else:
raise Exception('Conflict at %s' % '.'.join(path + [str(key)]))
# if the key isn't in a, add the rest of the b dictionary to a at this point
else:
dict_a[key] = dict_b[key]
return dict_a
# running:
merge_nested_dictionaries(dict_a, dict_b)
# returns:
{'ABC': {'DE': {'F': 'G', 'H': 'I'}, 'JKL': 'M'}}
how to merge two dictionaries with same keys in python
from collections import defaultdict
d1 = {1: 2, 3: 4}
d2 = {1: 6, 3: 7}
dd = defaultdict(list)
for d in (d1, d2): # you can list as many input dicts as you want here
for key, value in d.items():
dd[key].append(value)
print(dd)
def merge_dicts(dict1, dict2):
"""Here's an example of a for-loop being used abusively."""
return {**dict2, **{k: (v if not (k in dict2) else (v + dict2.get(k)) if isinstance(v, list) else merge_dicts(v, dict2.get(k))) if isinstance(v, dict) else v for k, v in dict1.items()}}
For dictionaries x and y, their shallowly-merged dictionary z takes values from y, replacing those from x.
In Python 3.9.0 or greater (released 17 October 2020, PEP-584, discussed here):
z = x | y
In Python 3.5 or greater:
z = {**x, **y}
In Python 2, (or 3.4 or lower) write a function:
def merge_two_dicts(x, y):
z = x.copy() # start with keys and values of x
z.update(y) # modifies z with keys and values of y
return z
and now:
z = merge_two_dicts(x, y)
# list_of_dictionaries contains a generic number of dictionaries
# having the same type of keys (str, int etc.) and type of values
global_dict = {}
for single_dict in list_of_dictionaries:
global_dict.update(single_dict)
yusuke_power = {"Yusuke Urameshi": "Spirit Gun"}
hiei_power = {"Hiei": "Jagan Eye"}
powers = dict()
# Brute force
for dictionary in (yusuke_power, hiei_power):
for key, value in dictionary.items():
powers[key] = value
# Dictionary Comprehension
powers = {key: value for d in (yusuke_power, hiei_power) for key, value in d.items()}
# Copy and update
powers = yusuke_power.copy()
powers.update(hiei_power)
# Dictionary unpacking (Python 3.5+)
powers = {**yusuke_power, **hiei_power}
# Backwards compatible function for any number of dicts
def merge_dicts(*dicts: dict):
merged_dict = dict()
for dictionary in dicts:
merge_dict.update(dictionary)
return merged_dict