python在pandas.DataFrame添加一行

    from pandas import *  
    from random import *  
    df = DataFrame(columns=('lib', 'qty1', 'qty2'))#生成空的pandas表  
    for i in range(5):#插入一行<span id="transmark" style="display: none; width: 0px; height: 0px;"></span>  
        df.loc[i] = [randint(-1,1) for n in range(3)]  
    print df