[Python]

文章从简书转入，只因它已不再是以前的简书

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The shortest distance between two people is a smile.
人与人之间最短的距离是微笑。

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List 列表实际操作练习

1、List 定义

>>> list = ["Mazy", "Joy", "Vivian", "Vicky", "Eric"]>>> list['Mazy', 'Joy', 'Vivian', 'Vicky', 'Eric']>>> list[3]'Vicky'

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2、List 负数索引

>>> list['Mazy', 'Joy', 'Vivian', 'Vicky', 'Eric']>>> list[-1]'Eric'>>> list[-3]'Vivian'>>> list['Mazy', 'Joy', 'Vivian', 'Vicky', 'Eric']>>> list[1:3]['Joy', 'Vivian']>>> list[1:-1]['Joy', 'Vivian', 'Vicky']>>> list[0:3]['Mazy', 'Joy', 'Vivian']

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3、List 增加元素

>>> list['Mazy', 'Joy', 'Vivian', 'Vicky', 'Eric']>>> list.append("Owen")>>> list['Mazy', 'Joy', 'Vivian', 'Vicky', 'Eric', 'Owen']>>> list.insert(2,"Lora")>>> list['Mazy', 'Joy', 'Lora', 'Vivian', 'Vicky', 'Eric', 'Owen']>>> list.extend(["666", "888"])>>> list['Mazy', 'Joy', 'Lora', 'Vivian', 'Vicky', 'Eric', 'Owen', '666', '888']

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4、List 搜索

>>> list['Mazy', 'Joy', 'Lora', 'Vivian', 'Vicky', 'Eric', 'Owen', '666', '888']>>> list.index("Vicky")4>>> list.index("666")7>>> list.index("Joy")1>>> "555" in listFalse>>> list.index("555")Traceback (most recent call last):  File "<stdin>", line 1, in <module>ValueError: '555' is not in list

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5、List 删除元素

>>> list['Mazy', 'Lora', 'Vivian', 'Vicky', 'Eric', 'Owen', '666', '888']>>> list.insert(1, "Joy")>>> list['Mazy', 'Joy', 'Lora', 'Vivian', 'Vicky', 'Eric', 'Owen', '666', '888']>>> list.insert(3, "666")>>> list['Mazy', 'Joy', 'Lora', '666', 'Vivian', 'Vicky', 'Eric', 'Owen', '666', '888']>>> list.remove("Joy")>>> list['Mazy', 'Lora', '666', 'Vivian', 'Vicky', 'Eric', 'Owen', '666', '888']>>> list.remove("666") # 删除首次出现的一个值>>> list['Mazy', 'Lora', 'Vivian', 'Vicky', 'Eric', 'Owen', '666', '888'] # 第二个 '666' 未删除>>> list.pop() # pop 会做两件事: 删除 list 的最后一个元素, 然后返回删除元素的值。'888'>>> list['Mazy', 'Lora', 'Vivian', 'Vicky', 'Eric', 'Owen', '666']>>> list.remove("555")  #list 中没有找到值, Python 会引发一个异常Traceback (most recent call last):  File "<stdin>", line 1, in <module>ValueError: list.remove(x): x not in list

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6、List 运算符

>>> list = ['Mazy', 'Lora', 'Vivian', 'Vicky']>>> list = list + ['Eric', 'Owen']>>> list['Mazy', 'Lora', 'Vivian', 'Vicky', 'Eric', 'Owen']>>> list += ["888"]>>> list['Mazy', 'Lora', 'Vivian', 'Vicky', 'Eric', 'Owen', '888']>>> num = [1, 2] * 3>>> num[1, 2, 1, 2, 1, 2]

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7.使用 Join 链接 List 成为字符串

join 只能用于元素是字符串的 list; 它不进行任何的类型强制转换。连接一个存在一个或多个非字符串元素的 list 将引发一个异常

>>> params = {"username":"Mazy", "password":"123456","uid":"001"}>>> ["%s=%s" % (k, v) for k, v in params.items()]['username=Mazy', 'password=123456', 'uid=001']>>> ";".join(["%s=%s" % (k, v) for k, v in params.items()])'username=Mazy;password=123456;uid=001'

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8、List 分割字符串

>>> list = ['username=Mazy', 'password=123456', 'uid=001']>>> s = ";".join(list)>>> s'username=Mazy;password=123456;uid=001'>>> s.split(";")['username=Mazy', 'password=123456', 'uid=001']>>> s.split(";",1)['username=Mazy', 'password=123456;uid=001']

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9、List 的映射解析

>>> li = [0, 8, 2 ,1]>>> [elem*2 for elem in li][0, 16, 4, 2]>>> li[0, 8, 2, 1]>>> li = [elem*2 for elem in li]>>> li[0, 16, 4, 2]

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10、Dictionary中的解析

>>> params = {"username":"Mazy", "password":"123456","uid":"001"}>>> params.keys()['username', 'password', 'uid']>>> params.values()['Mazy', '123456', '001']>>> params.items()[('username', 'Mazy'), ('password', '123456'), ('uid', '001')]>>> [k for k, v in params.items()]['username', 'password', 'uid']>>> [v for k, v in params.items()]['Mazy', '123456', '001']>>> ["%s=%s" % (k, v) for k, v in params.items()]['username=Mazy', 'password=123456', 'uid=001']

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11、List 过滤

>>> li = ["a", "ABC", "foo", "b", "y", "b", "d", "d"]>>> [elem for elem in li if len(elem) > 1]['ABC', 'foo']>>> [elem for elem in li if elem != "b"]['a', 'ABC', 'foo', 'y', 'd', 'd']>>> [elem for elem in li if li.count(elem) == 1]['a', 'ABC', 'foo', 'y']