Pandas Series数据结构基本操作

>>> import pandas
>>> import numpy as np
>>> from pandas import Series,DataFrame
#define a series without assigned index
>>> obj = Series([1,-5,7,3])
>>> print obj
0 1
1 -5
2 7
3 3
dtype: int64
>>> print obj.index
RangeIndex(start=0, stop=4, step=1)
>>> print obj.values
[ 1 -5 7 3]
>>> print obj[3]
3#explicitly assigned index dbac
>>> obj1 = Series([1,2,3,4],index=['d','b','a','c'])
>>> print obj1
d 1
b 2
a 3
c 4
dtype: int64
>>> print obj1.values
[1 2 3 4]
>>> print obj1.index
Index([u'd', u'b', u'a', u'c'], dtype='object')
>>> print obj1['c']
4
>>> obj1['a']=-4
>>> print obj1.values
[ 1 2 -4 4]#basic operation, index will not be changed
>>> obj1[obj1>0]
d 1
b 2
c 4
dtype: int64
>>> print obj1
d 1
b 2
a -4
c 4
dtype: int64
>>> obj2 = obj1[obj1>0]
>>> obj2
d 1
b 2
c 4
dtype: int64
>>> obj2*2
d 2
b 4
c 8
dtype: int64
>>> obj2
d 1
b 2
c 4
dtype: int64
>>> obj2 = obj2*2
>>> obj2
d 2
b 4
c 8
dtype: int64
>>> obj2=np.exp(obj2)
>>> obj2
d 7.389056
b 54.598150
c 2980.957987
dtype: float64
>>> 'b' in obj2
True
>>> 'e' in obj2
False

#define a Series with indexes and values
>>> sdata={'beijing':'010','shanghai':'021','guangdong':'020'}
>>> obj3 = Series(sdata)
>>> print obj3
beijing 010
guangdong 020
shanghai 021
dtype: object
>>> index1 = ['tianjin','shanghai','guangdong','beijing']
>>> obj3 = Series(sdata,index=index1)
>>> print obj3
tianjin NaN
shanghai 021
guangdong 020
beijing 010
dtype: object#isnull or notnull
>>> import pandas as pd
>>> print pd.isnull(obj3)
tianjin True
shanghai False
guangdong False
beijing False
dtype: bool
>>> print pd.notnull(obj3)
tianjin False
shanghai True
guangdong True
beijing True
dtype: bool

>>> obj3 = Series(sdata)
>>> print obj3
beijing 010
guangdong 020
shanghai 021
dtype: object
>>> index1 = ['tianjin','shanghai','guangdong','beijing']
>>> obj4 = Series(sdata,index=index1)
>>> print obj4
tianjin NaN
shanghai 021
guangdong 020
beijing 010
dtype: object
>>> print obj3+obj4
beijing 010010
guangdong 020020
shanghai 021021
tianjin NaN
dtype: object

>>> obj4.name='postcode'
>>> obj4.index.name='city'
>>> print obj4
city
tianjin NaN
shanghai 021
guangdong 020
beijing 010
Name: postcode, dtype: object