小编raf*_*ffa的帖子

我正在尝试选择df列label具有 value的行None。（这是None我从另一个函数获得的值，而不是NaN）

为什么df[df['label'].isnull()]返回我想要的行，

但df[df['label'] == None]返回Empty DataFrame Columns: [path, fanId, label, gain, order] Index: []？

我有一个字典,我想迭代并更改其值,但我认为长度的变化可能会导致错误,有没有什么好方法可以做到这一点？

例:

d = {'a':'orange','b':'pineapple','c':'dragonfruit'}
rating = {'orange':3, 'pineapple':4, 'dragonfruit':4.5, 'apple':3, 'pear': 3.5}

for key, value in d.items():
    if some conditions met:
        del d['a'] or d['e']='apple' # (or is not operator, i mean literally one of the operation add or delete item...)

例如:

for key, value in d.items():
    if rating[value]<4:
        del d[key]

要么

d = {'a':['orange'],'b':['pineapple','peach'],'c':['dragonfruit']}
rating = {'orange':3, 'pineapple':4, 'dragonfruit':4.5, 'apple':3, 'pear': 3.5, 'peach': 5}
for key, value in d.items():
    rating_sum = sum([ rating[v] for v in value])
    if …