python merge list of dictionaries by key value code example

Example 1: merge a list of dictionaries python

>>> from collections import ChainMap
>>> a = [{'a':1},{'b':2},{'c':1},{'d':2}]
>>> dict(ChainMap(*a))
{'b': 2, 'c': 1, 'a': 1, 'd': 2}

Example 2: python merge dictionaries

# 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}