pandas的基本用法05-索引

    # -*- coding: utf-8 -*- 
    import numpy as np
    from pandas import Series, DataFrame
    from numpy.core.defchararray import index

    print 'Series的索引，預設數字索引可以工作。'

    s = Series(np.arange(4.), index=['a','b','c','d'])
    print s[['a','b']]
    # a    0
    # b    1
    # dtype: float64
    print s[[0,1,2]]
    # a    0
    # b    1
    # c    2
    # dtype: float64
    print s[s>1]
    # c    2
    # d    3
    # dtype: float64

    print 'Series的陣列切片'
    print s['a':'c']
    # a    0
    # b    1
    # c    2
    # dtype: float64

    print 'DataFrame的索引'
    df = DataFrame(np.arange(16).reshape(4,4),
                   index = ['a', 'b','c','d'],
                   columns=[1,2,3,4]
                   )

    print df
    #     1   2   3   4
    # a   0   1   2   3
    # b   4   5   6   7
    # c   8   9  10  11
    # d  12  13  14  15

    print '列印列'
    print df[[1,2]]
    #     1   2
    # a   0   1
    # b   4   5
    # c   8   9
    # d  12  13
    print '列印行'
    print df[:2]
    #    1  2  3  4
    # a  0  1  2  3
    # b  4  5  6  7
    print df.ix[:2]
    #    1  2  3  4
    # a  0  1  2  3
    # b  4  5  6  7
    print '指定索引和列'
    print df.ix[['a','b'], [1,2,3]]
    #    1  2  3
    # a  0  1  2
    # b  4  5  6
    print df.ix[:'c', :3]
    #    1  2   3
    # a  0  1   2
    # b  4  5   6
    # c  8  9  10

    print '根據條件選擇'
    print df>3
    #        1      2      3      4
    # a  False  False  False  False
    # b   True   True   True   True
    # c   True   True   True   True
    # d   True   True   True   True
    print df[[1,2]]>3
    #        1      2
    # a  False  False
    # b   True   True
    # c   True   True
    # d   True   True
    df[df<3]=0
    print df
    #     1   2   3   4
    # a   0   0   0   3
    # b   4   5   6   7
    # c   8   9  10  11
    # d  12  13  14  15
    print df.T
    #    a  b   c   d
    # 1  0  4   8  12
    # 2  0  5   9  13
    # 3  0  6  10  14
    # 4  3  7  11  15