pandas 将索引值相加的方法

 s1 = pd.Series([1, 2, 3, 4], index=[\'a\', \'b\', \'c\', \'d\'])
 s2 = pd.Series([10, 20, 30, 40], index=[\'a\', \'b\', \'c\', \'d\'])
 print s1 + s2

a 11
b 22
c 33
d 44
dtype: int64

 s1 = pd.Series([1, 2, 3, 4], index=[\'a\', \'b\', \'c\', \'d\'])
 s2 = pd.Series([10, 20, 30, 40], index=[\'b\', \'d\', \'a\', \'c\'])
 print s1 + s2

a 31
b 12
c 43
d 24
dtype: int64

 s1 = pd.Series([1, 2, 3, 4], index=[\'a\', \'b\', \'c\', \'d\'])
 s2 = pd.Series([10, 20, 30, 40], index=[\'c\', \'d\', \'e\', \'f\'])
 print s1 + s2

a  NaN
b  NaN
c 13.0
d 24.0
e  NaN
f  NaN
dtype: float64

 s1 = pd.Series([1, 2, 3, 4], index=[\'a\', \'b\', \'c\', \'d\'])
 s2 = pd.Series([10, 20, 30, 40], index=[\'e\', \'f\', \'g\', \'h\'])
 print s1 + s2

a NaN
b NaN
c NaN
d NaN
e NaN
f NaN
g NaN
h NaN
dtype: float64