Python-12 序列

1、列表、元组、字符串的共同特点

-都可以通过索引得到每一个元素

-默认索引值总是从0开始

-可以通过分片的方法得到一个范围内的元素集合

-有很多共同的操作符（重复操作符、拼接操作符、成员关系操作符）

2、序列的常见BIF（内置方法）

-list(iterable) 

    把一个可迭代的对象转换为列表

    帮助文档

>>> help(list)Help on class list in module builtins:class list(object) |  list() -> new empty list |  list(iterable) -> new list initialized from iterable's items |   |  Methods defined here: |   |  __add__(self, value, /) |      Return self+value. |   |  __contains__(self, key, /) |      Return key in self. |   |  __delitem__(self, key, /) |      Delete self[key]. |   |  __eq__(self, value, /) |      Return self==value. |   |  __ge__(self, value, /) |      Return self>=value. |   |  __getattribute__(self, name, /) |      Return getattr(self, name). |   |  __getitem__(...) |      x.__getitem__(y) <==> x[y] |   |  __gt__(self, value, /) |      Return self>value. |   |  __iadd__(self, value, /) |      Implement self+=value. |   |  __imul__(self, value, /) |      Implement self*=value. |   |  __init__(self, /, *args, **kwargs) |      Initialize self.  See help(type(self)) for accurate signature. |   |  __iter__(self, /) |      Implement iter(self). |   |  __le__(self, value, /) |      Return self<=value. |   |  __len__(self, /) |      Return len(self). |   |  __lt__(self, value, /) |      Return self<value. |   |  __mul__(self, value, /) |      Return self*value.n |   |  __ne__(self, value, /) |      Return self!=value. |   |  __new__(*args, **kwargs) from builtins.type |      Create and return a new object.  See help(type) for accurate signature. |   |  __repr__(self, /) |      Return repr(self). |   |  __reversed__(...) |      L.__reversed__() -- return a reverse iterator over the list |   |  __rmul__(self, value, /) |      Return self*value. |   |  __setitem__(self, key, value, /) |      Set self[key] to value. |   |  __sizeof__(...) |      L.__sizeof__() -- size of L in memory, in bytes |   |  append(...) |      L.append(object) -> None -- append object to end |   |  clear(...) |      L.clear() -> None -- remove all items from L |   |  copy(...) |      L.copy() -> list -- a shallow copy of L |   |  count(...) |      L.count(value) -> integer -- return number of occurrences of value |   |  extend(...) |      L.extend(iterable) -> None -- extend list by appending elements from the iterable |   |  index(...) |      L.index(value, [start, [stop]]) -> integer -- return first index of value. |      Raises ValueError if the value is not present. |   |  insert(...) |      L.insert(index, object) -- insert object before index |   |  pop(...) |      L.pop([index]) -> item -- remove and return item at index (default last). |      Raises IndexError if list is empty or index is out of range. |   |  remove(...) |      L.remove(value) -> None -- remove first occurrence of value. |      Raises ValueError if the value is not present. |   |  reverse(...) |      L.reverse() -- reverse *IN PLACE* |   |  sort(...) |      L.sort(key=None, reverse=False) -> None -- stable sort *IN PLACE* |   |  ---------------------------------------------------------------------- |  Data and other attributes defined here: |   |  __hash__ = None>>> 

空列表

字符串 迭代成一个列表

>>> a=list()>>> a[]>>> b='beijing'>>> b=list(b)>>> b['b', 'e', 'i', 'j', 'i', 'n', 'g']>>> 

元组 迭代成一个列表

>>> c = (1,1,2,3,5,8,13,21,34)>>> c = list(c)>>> c[1, 1, 2, 3, 5, 8, 13, 21, 34]>>> 

  -tuple([iterable])

把一个可迭代对象转换为元组

空元组

字符串 ->元组

列表 -> 元组

>>> a = tuple()>>> a()>>> a = 'beijing'>>> a = tuple(a)>>> a('b', 'e', 'i', 'j', 'i', 'n', 'g')>>> b = ['beijing']>>> b = tuple(b)>>> b('beijing',)>>> b[0]'beijing'

-str(obj)

把obj对象转换为字符串

>>> a = (1,1,2,3,5)>>> a = str(a)>>> a'(1, 1, 2, 3, 5)'>>> len(a)15>>> num = [1,1,2,3,5,8]>>> sum(num)20>>> for i in a:print(i)(1, 1, 2, 3, 5)>>> 

-len(sub)

返回sub的长度

-max()

返回序列或参数集合中的最大值

>>> max(1,3,5,2)5>>> max([1,4,2,7,3]) #列表7>>> max('1,7,2,9,4,6,4')'9'>>> max((1,7,2,9,4,6,4)) #元组9>>> >>> b = 'beijing'>>> b = list(b)>>> b['b', 'e', 'i', 'j', 'i', 'n', 'g']>>> max(b)'n'>>> #ascii码

-min()

返回序列或参数集合中的最小值

>>> b = 'beijing'>>> b = list(b)>>> b['b', 'e', 'i', 'j', 'i', 'n', 'g']>>> min(1,3,5,-2)-2>>> min([1,4,2,7,-3])-3>>> min('1,7,-2,9,4,6,4')','>>> min(b)'b'>>> >>> num = '1234567890'>>> min(num)'0'>>> 

-sum(iterable[,start=0])

返回序列iterable和可选参数start的总和

>>> num = [1,1,2,3,5,8]>>> sum(num)20>>> tuple1 = (1.2,4.5,2.6)>>> sum(tuple1)8.3>>> sum(tuple1,1.1)9.4>>> 

-sorted(iterable,key=None,reverse=False)

返回一个排序的列表，使用方法和列表内置函数（list.sort()）一致。

>>> b['b', 'e', 'i', 'j', 'i', 'n', 'g']>>> sorted(b)['b', 'e', 'g', 'i', 'i', 'j', 'n']>>> c = 'beijing'>>> sorted(c)['b', 'e', 'g', 'i', 'i', 'j', 'n']>>> 

-reversed(sequence)

返回逆向迭代序列的值，和列表内置函数（list.reverse()）一致。

>>> num[1, 1, 2, 3, 5, 8]>>> reversed(num)<list_reverseiterator object at 0x022BFC50>>>> list(reversed(num))[8, 5, 3, 2, 1, 1]>>> 

-enumerate(iterable)

生成由每个元素的index和item值组成的元组

>>> c'beijing'>>> enumerate(c)<enumerate object at 0x022B2508>>>> tuple(enumerate(c))((0, 'b'), (1, 'e'), (2, 'i'), (3, 'j'), (4, 'i'), (5, 'n'), (6, 'g'))>>> >>> list(enumerate(c))[(0, 'b'), (1, 'e'), (2, 'i'), (3, 'j'), (4, 'i'), (5, 'n'), (6, 'g')]>>> 

-zip(iter1 [,iter2 [...]])

返回由各个参数的序列组成的元组

>>> d = [1,2,4,5,6]>>> e = [7,8,1,2]>>> zip(d,e)<zip object at 0x022A3788>>>> list(zip(d,e))[(1, 7), (2, 8), (4, 1), (5, 2)]>>> tuple(zip(d,e))((1, 7), (2, 8), (4, 1), (5, 2))>>>