Python学习-append（）函数

append() 方法用于在列表末尾添加新的对象。

如下实例：

list1 = ['Google', 'Runoob', 'Taobao']
list1.append('Baidu')
print ("更新后的列表 : ", list1)

输出结果：

更新后的列表 :  ['Google', 'Runoob', 'Taobao', 'Baidu']

在练习过程中，遇到一个元素为列表的列表使用append（）函数，简单几句代码就完成了列表的赋值。

代码内容:

target_file = 'E:\Anaconda\climate.txt'
with open(target_file,'r',encoding='utf-8') as fp:
    raw_data = fp.readlines()   
climate_data = []
for item in raw_data:
    climate_data.append(item.rstrip('\n').split('\t'))

climate.txt的内容是各城市每个月的平均温度：

climate_data.append(item.rstrip('\n').split('\t'))

当 list 类型的对象进行 append 操作时，实际上追加的是该对象的引用，是浅拷贝。climate_date.append()是在climate_data列表中引用一个个列表item，climate_date[0]记录的是item的内存地址。同时，item又有切片和去尾处理，因此最终climate_data打印出来是一个元素为列表的列表。

在代码最后一行打印climate_data：

[['北京', '-4.7', '-1.4', '6.2', '12.6', '21.9', '23.8', '27.4', '27.3', '20.7', '13.6', '6.3', '0.1', '12.8'], ['天津', '-4.7', '-1.2', '5.9', '12.0', '21.5', '24.5', '27.0', '27.7', '21.2', '13.9', '6.3', '-0.7', '12.8'], ['石家庄', '-4.2', '-0.4', '8.7', '13.8', '22.2', '24.9', '27.3', '27.9', '21.4', '14.7', '8.1', '17', '13.8'], ['太原', '-5.1', '-0.8', '7.9', '12.0', '20.4', '22.7', '23.3', '23.6', '17.8', '11.6', '3.6', '-3.2', '11.2'], ['呼和浩特', '-10.9', '-6.0', '2.3', '8.0', '18.0', '20.6', '21.5', '20.6', '15.1', '7.8', '-1.5', '-8.1', '7.3'], ['沈阳', '-14.2', '-8.8', '-0.5', '6.5', '19.1', '22.5', '25.1', '24.3', '17.6', '9.4', '1.6', '-8.1', '7.9'], ['长春', '-17.4', '-13.5', '-4.3', '4.1', '17.9', '21.3', '23.7', '22.6', '16.4', '8.3', '-0.8', '-11.2', '5.6'], ['哈尔滨', '-21.1', '-16.4', '-7.4', '4.4', '17.9', '21.4', '23.9', '22.5', '15.8', '7.0', '-2.6', '-14.0', '4.3'], ['上海', '4.6', '6.8', '11.0', '15.3', '21.3', '24.1', '32.0', '31.0', '25.0', '20.0', '13.4', '6.1', '17.6'], ['南京', '3.0', '5.5', '10.8', '16.0', '21.7', '24.3', '30.5', '30.8', '23.6', '18.4', '12.1', '4.7', '16.8'], ['杭州', '4.5', '7.0', '12.3', '16.9', '23.0', '24.8', '32.3', '31.3', '25.0', '19.3', '13.6', '6.3', '18.0'], ['合肥', '2.8', '5.9', '11.9', '17.0', '22.5', '25.3', '30.2', '31.1', '23.6', '18.3', '11.4', '3.6', '17.0'], ['福州', '10.6', '12.7', '15.1', '17.4', '22.9', '26.7', '29.8', '29.6', '26.8', '22.9', '17.8', '12.0', '20.4'], ['南昌', '5.6', '8.0', '14.1', '17.5', '24.0', '26.9', '30.9', '31.6', '25.7', '20.8', '14.8', '7.8', '19.0'], ['济南', '-1.6', '1.9', '9.3', '14.2', '22.1', '25.7', '27.6', '28.6', '22.7', '16.4', '8.2', '1.8', '14.7'], ['郑州', '-0.5', '3.1', '11.0', '16.0', '22.8', '27.0', '29.1', '30.1', '23.5', '17.2', '9.7', '3.6', '16.1'], ['武汉', '2.9', '5.9', '12.9', '17.1', '22.1', '26.1', '30.6', '30.6', '22.9', '18.2', '11.4', '4.5', '17.1'], ['']]