python merge nested dictionaries code example

Example 1: python merge two dictionaries in a single expression

z = {**x, **y}  #python 3.5 and above

z = x | y    #python 3.9+ ONLY

def merge_two_dicts(x, y): # python 3.4 or lower
      z = x.copy()   # start with x's keys and values
      z.update(y)    # modifies z with y's keys and values & returns None
      return z

Example 2: 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}