pandas NaN的操作

1.1NaN in Series

s1 = pd.Series([1,2,np.nan,3,4],index=["a","b","c","d","e"])

1 s1.isnull()# s1.notnull() 返回bool
2 a    False
3 b    False
4 c     True
5 d    False
6 e    False
7 dtype: bool

删除nan

1 s1.dropna()#去掉nan的项
2 a    1.0
3 b    2.0
4 d    3.0
5 e    4.0
6 dtype: float64

1.2 NaN in DataFrame 

df.isnull()  生成所有数据的true／false矩阵  

df.isnull().any()则会判断哪些”列”存在缺失值

df.isnull().all() 只有在那一列全为NAN时才会返回True

df.notnull()同理

df.dropna(axis=0, how=‘any‘, thresh=None, subset=None, inplace=False)

df.fillna(value=None, method=None, axis=None, inplace=False, limit=None, downcast=None, **kwargs)