comparing two dict in python to get the maximum value for similar key

问题

I have these 2 dicts:

a={"test1":90,  "test2":45,  "test3":67,  "test4":74}
b={"test1":32,  "test2":45,  "test3":82,  "test4":100}

how to extract the maximum value for the same key to get new dict as this below:

c={"test1":90,  "test2":45,  "test3":82,  "test4":100}

回答1:

You can try like this,

>>> a={"test1":90, "test2":45, "test3":67, "test4":74} 
>>> b={"test1":32, "test2":45, "test3":82, "test4":100}
>>> c = { key:max(value,b[key]) for key, value in a.iteritems() }
>>> c
{'test1': 90, 'test3': 82, 'test2': 45, 'test4': 100}

回答2:

Try this:

>>> a={"test1":90, "test2":45, "test3":67, "test4":74} 
>>> b={"test1":32, "test2":45, "test3":82, "test4":100}
>>> c={ k:max(a[k],b[k]) for k in a if b.get(k,'')}
{'test1': 90, 'test3': 82, 'test2': 45, 'test4': 100}

回答3:

Not the best, but still a variant:

from itertools import chain

a = {'test1':90, 'test2': 45, 'test3': 67, 'test4': 74}
b = {'test1':32, 'test2': 45, 'test3': 82, 'test4': 100, 'test5': 1}

c = dict(sorted(chain(a.items(), b.items()), key=lambda t: t[1]))
assert c == {'test1': 90, 'test2': 45, 'test3': 82, 'test4': 100, 'test5': 1}

来源：https://stackoverflow.com/questions/25658540/comparing-two-dict-in-python-to-get-the-maximum-value-for-similar-key