Python3基础——序列类型

开头写给自己，To Myself：

很久以来，都想要学习一门编程语言，从去年选择了python开始，反反复复重新开始了N多遍，每一次不会超过俩星期。昨天无意间翻开自己去年记的学习笔记，不禁感叹想当年我曾那么用功，却未能坚持下来，着实可惜。这一次，我告诉自己，最后一次机会，必须坚持到底！must。。。。。。

Sequence Types — `list`, `tuple`, `range`

Common Sequence Operations

Operation	Result	Notes
`x in s`	`True` if an item of s is equal to x, else `False——关系操作符`	(1)
`x not in s`	`False` if an item of s is equal to x, else `True——关系操作符`	(1)
`s + t`	the concatenation of s and t——连接操作符	(6)(7)
`s * n` or `n * s`	equivalent to adding s to itself n times——重复操作符	(2)(7)
`s[i]`	ith item of s, origin 0——获取下标位i的元素，下标从0开始	(3)
`s[i:j]`	slice of s from i to j——切片拷贝	(3)(4)
`s[i:j:k]`	slice of s from i to j with step k	(3)(5)
`len(s)`	length of s
`min(s)`	smallest item of s
`max(s)`	largest item of s
`s.index(x[, i[, j]])`	index of the first occurrence of x in s (at or after index i and before index j) 元素x在s中最早出现的位置下标，可以设置下标所在范围的起始位置	(8)
`s.count(x)`	total number of occurrences of x in s——元素x在序列s中出现的次数

Immutable Sequence Types

hash()

Mutable Sequence Types

Operation	Result	Notes
`s[i] = x`	item i of s is replaced by x
`s[i:j] = t`	slice of s from i to j is replaced by the contents of the iterable t
`del s[i:j]`	same as `s[i:j] = []`
`s[i:j:k] = t`	the elements of `s[i:j:k]` are replaced by those of t	(1)
`del s[i:j:k]`	removes the elements of `s[i:j:k]` from the list
`s.append(x)`	appends x to the end of the sequence (same as `s[len(s):len(s)] = [x]`)
`s.clear()`	removes all items from `s` (same as `del s[:]`)	(5)
`s.copy()`	creates a shallow copy of `s` (same as `s[:]`)	(5)
`s.extend(t)` or `s += t`	extends s with the contents of t (for the most part the same as `s[len(s):len(s)] = t`)
`s *= n`	updates s with its contents repeated n times	(6)
`s.insert(i, x)`	inserts x into s at the index given by i (same as `s[i:i] = [x]`)
`s.pop([i])`	retrieves the item at i and also removes it from s	(2)
`s.remove(x)`	remove the first item from s where `s[i] == x`	(3)
`s.reverse()`	reverses the items of s in place	(4)

Lists

1、创建列表的方法：

Using a pair of square brackets to denote the empty list: []
Using square brackets, separating items with commas: [a], [a, b, c]
Using a list comprehension: [x for x in iterable]
Using the type constructor: list() or list(iterable)

　　　　list('abc') returns ['a', 'b', 'c']

　　　　list( (1, 2, 3) ) returns [1, 2, 3]

2、除了以上方法外，列表还支持sort()方法

　　sort(*, key=None, reverse=None)

对列表进行排序，默认是按照从小到大的顺序排列

Tuples

1、创建元组的方法：

Using a pair of parentheses to denote the empty tuple: ()
Using a trailing comma for a singleton tuple: a, or (a,)
Separating items with commas: a, b, c or (a, b, c)
Using the tuple() built-in: tuple() or tuple(iterable)

For example, tuple('abc') returns ('a', 'b', 'c') and tuple( [1, 2, 3] ) returns (1, 2, 3).

注意：当你要创建的元组只有一个元素时，必须带逗号

Ranges

代表一组不可变的数字序列，主要用于for循环

class range(stop)

class range(start, stop[, step])

参数必须为整数，step步幅默认为1，start开始参数默认为0、

>>> list(range(10))

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>>> list(range(1, 11))

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

>>> list(range(0, 30, 5))

[0, 5, 10, 15, 20, 25]

>>> list(range(0, 10, 3))

[0, 3, 6, 9]

>>> list(range(0, -10, -1))

[0, -1, -2, -3, -4, -5, -6, -7, -8, -9]

>>> list(range(0))

[]

>>> list(range(1, 0))

[]

列表、元组、字符串总结
共同点：
都可以通过索引得到每一个元素
默认索引值从0开始
可以用通过分片得到一个范围内的元素的集合
有很多共同的操作符（重复、拼接、成员关系操作符）