Question

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

如果值为0，我想将值更改为None。我怎么能这样做？

例如：

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

我想将foo和bar更改为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

另一种方式

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

实施例

>>> 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

Answer 5

如果你想恐吓或惹恼其他代码维护者，那么就会有一个丑陋的单行代码可以解决这个问题：

records.update(map(lambda (k,v):(k,{v:v,None:0}[v]), records.items()))

使用示例：

>>> records = {"hey":None, "you":0}
>>> records.update(map(lambda (k,v):(k,{v:v,None:0}[v]), records.items()))
>>> records
{'you': 0, 'hey': 0}

Answer 6

records = dict( ( k,0 if v is None else v ) for k, v in records.items() )

def zero_if_none( x ):
    return 0 if x is None else x
records = dict( ( k, zero_if_none( records[k] ) ) for k in records )

如何遍历一个字典？

6 个答案: