如何遍历一个字典？

Question

records = {'foo':foo, 'bar':bar, 'baz':baz}

我想将值更改为0if None.我怎样才能做到这一点？

例如:

records = {'foo':None, 'bar':None, 'baz':1}

我想改变foo和bar到0.最后的决定:

records = {'foo':0, 'bar':0, 'baz':1}

Answer 1

for k in records:
    if records[k] is None:
        records[k] = 0

Answer 2

其他方式

records.update((k, 0) for k,v in records.iteritems() if v is None)

例

>>> records
{'bar': None, 'baz': 1, 'foo': None}
>>> records.update((k, 0) for k,v in records.iteritems() if v is None)
>>> records
{'bar': 0, 'baz': 1, 'foo': 0}

Answer 3

尝试

for key, value in records.iteritems():
    if value is None:
        records[key] = 0

Answer 4

for k, v in records.items():
    if v is None:
        records[k] = 0