字符串
元组
集合
字典
我们在前面章节已经看到过字符串区间列表等序列类型元组是另外一中序列类型这一章我们学习更多关于字符串元组字典和集合的操作
字符串
我们之前看到在列表中使用的索引也可以应用于字符串
因为字符串不可变长, 它们不能像列表一样修改
- >>> book = "Alchemist"
- >>> book[0]
- 'A'
- >>> book[3]
- 'h'
- >>> book[-1]
- 't'
- >>> book[10]
- Traceback (most recent call last):
- File "<stdin>", line 1, in <module>
- IndexError: string index out of range
- >>> book[2:6]
- 'chem'
- >>> book[:5]
- 'Alche'
- >>> book[5:]
- 'mist'
- >>> book[::-1]
- 'tsimehclA'
- >>> book[:]
- 'Alchemist'
- >>> list(book)
- ['A', 'l', 'c', 'h', 'e', 'm', 'i', 's', 't']
- >>> import string
- >>> string.ascii_lowercase[:10]
- 'abcdefghij'
- >>> list(string.digits)
- ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
字符串循环操作
- >>> book
- 'Alchemist'
- >>> for char in book:
- ... print(char)
- ...
- A
- l
- c
- h
- e
- m
- i
- s
- t
其他操作
- >>> book
- 'Alchemist'
- >>> len(book)
- 9
- >>> book.index('A')
- 0
- >>> book.index('t')
- 8
- >>> 'A' in book
- True
- >>> 'B' in book
- False
- >>> 'z' not in book
- True
- >>> min('zealous')
- 'a'
- >>> max('zealous')
- 'z'
元组
元素跟列表相似, 但是不可变长, 在其他场景中很有用
单一的元素可变长 / 不变长
- >>> north_dishes = ('Aloo tikki', 'Baati', 'Khichdi', 'Makki roti', 'Poha')
- >>> north_dishes
- ('Aloo tikki', 'Baati', 'Khichdi', 'Makki roti', 'Poha')
- >>> north_dishes[0]
- 'Aloo tikki'
- >>> north_dishes[-1]
- 'Poha'
- >>> north_dishes[6]
- Traceback (most recent call last):
- File "<stdin>", line 1, in <module>
- IndexError: tuple index out of range
- >>> north_dishes[::-1]
- ('Poha', 'Makki roti', 'Khichdi', 'Baati', 'Aloo tikki')
- >>> north_dishes[0] = 'Poori'
- Traceback (most recent call last):
- File "<stdin>", line 1, in <module>
- TypeError: 'tuple' object does not support item assignment
示例操作
- >>> 'roti' in north_dishes
- False
- >>> 'Makki roti' in north_dishes
- True
- >>> len(north_dishes)
- 5
- >>> min(north_dishes)
- 'Aloo tikki'
- >>> max(north_dishes)
- 'Poha'
- >>> for dish in north_dishes:
- ... print(dish)
- ...
- Aloo tikki
- Baati
- Khichdi
- Makki roti
- Poha
元组用于处理多个变量分配 (赋值) 和在函数中返回多个值
在使用 enumerate 用于迭代列表时我们已经看过例子了
- >>> a = 5
- >>> b = 20
- >>> a, b = b, a
- >>> a
- 20
- >>> b
- 5
- >>> c = 'foo'
- >>> a, b, c = c, a, b
- >>> a
- 'foo'
- >>> b
- 20
- >>> c
- 5
- >>> def min_max(arr):
- ... return min(arr), max(arr)
- ...
- >>> min_max([23, 53, 1, -34, 9])
- (-34, 53)
并不总需要使用()
- >>> words = 'day', 'night'
- >>> words
- ('day', 'night')
- >>> coordinates = ((1,2), (4,3), (92,3))
- >>> coordinates
- ((1, 2), (4, 3), (92, 3))
- >>> prime = [2, 3, 5, 7, 11]
- >>> prime_tuple = tuple((idx + 1, num) for idx, num in enumerate(prime))
- >>> prime_tuple
- ((1, 2), (2, 3), (3, 5), (4, 7), (5, 11))
将其他类型转换为元组
与 list()相似
- >>> tuple('books')
- ('b', 'o', 'o', 'k', 's')
- >>> a = [321, 899.232, 5.3, 2, 1, -1]
- >>> tuple(a)
- (321, 899.232, 5.3, 2, 1, -1)
数据类型可用多种方式混合和匹配
- >>> a = [(1,2), ['a', 'b'], ('good', 'bad')]
- >>> a
- [(1, 2), ['a', 'b'], ('good', 'bad')]
- >>> b = ((1,2), ['a', 'b'], ('good', 'bad'))
- >>> b
- ((1, 2), ['a', 'b'], ('good', 'bad'))
Python 文档 - 元组
Python 文档 - 元组教程
集合
集合是无序的对象集
可变数据类型
通常用于保持唯一的序列执行集合操作(像交并差等等)
- >>> nums = {3, 2, 5, 7, 1, 6.3}
- >>> nums
- {1, 2, 3, 5, 6.3, 7}
- >>> primes = {3, 2, 11, 3, 5, 13, 2}
- >>> primes
- {2, 3, 11, 13, 5}
- >>> nums.union(primes)
- {1, 2, 3, 5, 6.3, 7, 11, 13}
- >>> primes.difference(nums)
- {11, 13}
- >>> nums.difference(primes)
- {1, 6.3, 7}
示例操作
- >>> len(nums)
- 6
- >>> nums[0]
- Traceback (most recent call last):
- File "<stdin>", line 1, in <module>
- TypeError: 'set' object does not support indexing
- >>> book
- 'Alchemist'
- >>> set(book)
- {'i', 'l', 's', 'A', 'e', 'h', 'm', 't', 'c'}
- >>> set([1, 5, 3, 1, 9])
- {1, 9, 3, 5}
- >>> list(set([1, 5, 3, 1, 9]))
- [1, 9, 3, 5]
- >>> nums = {1, 2, 3, 5, 6.3, 7}
- >>> nums
- {1, 2, 3, 5, 6.3, 7}
- >>> nums.pop()
- 1
- >>> nums
- {2, 3, 5, 6.3, 7}
- >>> nums.add(1)
- >>> nums
- {1, 2, 3, 5, 6.3, 7}
- >>> 6.3 in nums
- True
- >>> for n in nums:
- ... print(n)
- ...
- 1
- 2
- 3
- 5
- 6.3
- 7
Python 文档 - 集合
Python 文档 - frozenset
集合教程
字典
字典类型被看作无序的键值对或有名字的元素列表
- >>> marks = {'Rahul' : 86, 'Ravi' : 92, 'Rohit' : 75}
- >>> marks
- {'Ravi': 92, 'Rohit': 75, 'Rahul': 86}
- >>> fav_books = {}
- >>> fav_books['fantasy'] = 'Harry Potter'
- >>> fav_books['detective'] = 'Sherlock Holmes'
- >>> fav_books['thriller'] = 'The Da Vinci Code'
- >>> fav_books
- {'thriller': 'The Da Vinci Code', 'fantasy': 'Harry Potter', 'detective': 'Sherlock Holmes'}
- >>> marks.keys()
- dict_keys(['Ravi', 'Rohit', 'Rahul'])
- >>> fav_books.values()
- dict_values(['The Da Vinci Code', 'Harry Potter', 'Sherlock Holmes'])
循环和打印
- >>> for book in fav_books.values():
- ... print(book)
- ...
- The Da Vinci Code
- Harry Potter
- Sherlock Holmes
- >>> for name, mark in marks.items():
- ... print(name, mark, sep=':')
- ...
- Ravi: 92
- Rohit: 75
- Rahul: 86
- >>> import pprint
- >>> pp = pprint.PrettyPrinter(indent=4)
- >>> pp.pprint(fav_books)
- { 'detective': 'Sherlock Holmes',
- 'fantasy': 'Harry Potter',
- 'thriller': 'The Da Vinci Code'}
修改字典和示例操作
- >>> marks
- {'Ravi': 92, 'Rohit': 75, 'Rahul': 86}
- >>> marks['Rajan'] = 79
- >>> marks
- {'Ravi': 92, 'Rohit': 75, 'Rahul': 86, 'Rajan': 79}
- >>> del marks['Ravi']
- >>> marks
- {'Rohit': 75, 'Rahul': 86, 'Rajan': 79}
- >>> len(marks)
- 3
- >>> fav_books
- {'thriller': 'The Da Vinci Code', 'fantasy': 'Harry Potter', 'detective': 'Sherlock Holmes'}
- >>> "fantasy" in fav_books
- True
- >>> "satire" in fav_books
- False
字典由列表组成并使用随机模块
任何对单个列表的改变会反映在字典中
keys()方法的输出必须改变为像 list 或者 tuple 这样的序列类型传入 random.choice
- >>> north = ['aloo tikki', 'baati', 'khichdi', 'makki roti', 'poha']
- >>> south = ['appam', 'bisibele bath', 'dosa', 'koottu', 'sevai']
- >>> west = ['dhokla', 'khakhra', 'modak', 'shiro', 'vada pav']
- >>> east = ['hando guri', 'litti', 'momo', 'rosgulla', 'shondesh']
- >>> dishes = {'North': north, 'South': south, 'West': west, 'East': east}
- >>> rand_zone = random.choice(tuple(dishes.keys()))
- >>> rand_dish = random.choice(dishes[rand_zone])
- >>> print("Try the'{}'speciality'{}'today".format(rand_zone, rand_dish))
- Try the 'East' speciality 'rosgulla' today
进一步阅读
Python 文档 - 字典
Python 文档 - pprint
字典详细教程
来源: http://www.jianshu.com/p/d27050ef63f6