Created
December 23, 2012 18:07
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Merge two hashes/dictionaries in Ruby and Python.
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h1 = { "a" => 100, "b" => 200 } | |
h2 = { "b" => 254, "c" => 300 } | |
h3 = h1.merge(h2) | |
h3 #=> {"a"=>100, "b"=>254, "c"=>300} | |
h1 #=> { "a" => 100, "b" => 200 } |
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>>> x = {'a':1, 'b': 2} | |
>>> y = {'b':10, 'c': 11} | |
>>> z = x.update(y) | |
>>> print z | |
None | |
>>> x | |
{'a': 1, 'b': 10, 'c': 11} |
That's only valid syntax in Python 3.5. In Python 2, you could do
x = {'a': 1}
y = {'b': 2}
z = dict(x, **y)
x = {**x, **y} # not the same as
x.update(y)
# because a new dict is constructed and assigned to x
x = {'x': 'xxxx'}
y = {'y': 'yyyy'}
id(x), id(y)
(140215338406176, 140215338368816)
x = {**x, **y}; x
{'x': 'xxxx', 'y': 'yyyy'}
id(x)
140215338405960
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Today I discovered that there is a nice way to "merge" dictionaries in Python:
This is very useful because you can get assign this result to a new dictionary or update the existing one: