setdefault

2021-07-09 本文已影响0人 QXPLUS

my_dict.setdefault(key, []).append(new_value)

testdict = {}
testdict.setdefault('PRJ', [])

print(testdict)

{'PRJ': []}

lst = []
RR_list = [1,2,3,4,5]
lst.append(RR_list)

print(lst)

[[1, 2, 3, 4, 5]]

testdict = {}
RR_list = [1,2,3,4,5]
testdict.setdefault('PRJ', []).append(RR_list)

print(testdict)

{'PRJ': [[1, 2, 3, 4, 5]]}

testdict = {}
for i in range(3):
    RR_list = [1,2,3,4,5]
    testdict.setdefault('PRJ', []).append(RR_list)

print(testdict)

{'PRJ': [[1, 2, 3, 4, 5], [1, 2, 3, 4, 5], [1, 2, 3, 4, 5]]}