python中，数据结构是通过某种方式(例如对元素进行编号),组织在一起数据结构的集合．

python常用的组合数据类型有：序列类型，集合类型和映射类型    在序列类型中，又可以分为列表和元组，字符串也属于序列类型    在集合类型中，主要有集合类型    在映射类型中，主要有字典类型，字典是可变序列

python中一切皆对象，组合数据类型也是对象，因此python的组合数据类型可以嵌套使用，列表中可以嵌套元组和字典，元组中也可以嵌套和字典，当然字典中也可以嵌套元组和列表，例如：['hello','world',[1,2,3]]

元组，列表以及字符串等数据类型是"有大小的"，也即其长度可使用内置函数len()测量python对象可以具有其可以被调用的特定“方法(函数)”

列表的常用内置方法

在python中，列表使用[]创建，例如['hello','world','linux','python']列表是可变序列，其主要表现为：列表中的元素可以根据需要扩展和移除，而列表的内存映射地址不改变  列表属于序列类型，可以在python解释器中使用dir(list)查看列表的内置方法

append

#在列表的末尾添加元素L.append(object) -- append object to end

>>> l1=["hello","world"]>>> l2=[1,2,3,4]>>> l1.append("linux")>>> print(l1)['hello', 'world', 'linux']>>> l2.append(5)>>> print(l2)[1, 2, 3, 4, 5]

clear

#清除列表中的所有元素L.clear() -> None -- remove all items from L

>>> l1=["hello","world"]>>> l2=[1,2,3,4]>>> l1.clear()>>> print(l1)[]>>> l2.clear()>>> print(l2)[]

copy

#浅复制L.copy() -> list -- a shallow copy of L

>>> l1=["hello","world","linux"]>>> id(l1)140300326525832>>> l2=l1.copy()>>> id(l2)140300326526024>>> print(l1)['hello', 'world', 'linux']>>> print(l2)['hello', 'world', 'linux']

count

#返回某个元素在列表中出现的次数L.count(value) -> integer -- return number of occurrences of value

>>> l1=[1,2,3,4,2,3,4,1,2]>>> l1.count(1)2>>> l1.count(2)3>>> l1.count(4)2

extend

#把另一个列表扩展进本列表中L.extend(iterable) -- extend list by appending elements from the iterable

>>> l1=["hello","world"]>>> l2=["linux","python"]>>> l1.extend(l2)>>> print(l1)['hello', 'world', 'linux', 'python']

index

#返回一个元素第一次出现在列表中的索引值，如果元素不存在报错L.index(value, [start, [stop]]) -> integer -- return first index of value.　Raises ValueError if the value is not present.

>>> l1=[1,2,3,4,2,3,4,1,2]    >>> l1.index(1)    0    >>> l1.index(2)    1    >>> l1.index(4)    3    >>> l1.index(5)    Traceback (most recent call last):      File "
    
     ", line 1, in 
     
          ValueError: 5 is not in list
     
    

insert

#在这个索引之前插入一个元素L.insert(index, object) -- insert object before index

>>> l1=['hello', 'world', 'linux', 'python']    >>> l1.insert(1,"first")    >>> print(l1)    ['hello', 'first', 'world', 'linux', 'python']    >>> l1.insert(1,"second")    >>> print(l1)    ['hello', 'second', 'first', 'world', 'linux', 'python']

pop

#移除并返回一个索引上的元素，如果是一个空列表或者索引的值超出列表的长度则报错L.pop([index]) -> item -- remove and return item at index (default last).Raises IndexError if list is empty or index is out of range.

>>> l1=['hello', 'world', 'linux', 'python']    >>> l1.pop()    'python'    >>> l1.pop(1)    'world'    >>> l1.pop(3)    Traceback (most recent call last):      File "
    
     ", line 1, in 
     
          IndexError: pop index out of range
     
    

remove

#移除第一次出现的元素，如果元素不存在则报错L.remove(value) -- remove first occurrence of value.Raises ValueError if the value is not present.

>>> l1=['hello', 'world', 'linux', 'python']    >>> l1.remove("hello")    >>> print(l1)    ['world', 'linux', 'python']    >>> l1.remove("linux")    >>> print(l1)    ['world', 'python']    >>> l1.remove("php")    Traceback (most recent call last):      File "
    
     ", line 1, in 
     
          ValueError: list.remove(x): x not in list
     
    

reverse

#原地反转列表L.reverse() -- reverse *IN PLACE*

>>> l1=['hello', 'world', 'linux', 'python']    >>> id(l1)    140300326525832    >>> l1.reverse()####    >>> print(l1)    ['python', 'linux', 'world', 'hello']    >>> id(l1)    140300326525832

sort

#对列表进行原地排序L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*;

>>> l1=[1,3,5,7,2,4,6,8]    >>> id(l1)    140300326526024    >>> l1.sort()    >>> print(l1)    [1, 2, 3, 4, 5, 6, 7, 8]    >>> id(l1)    140300326526024

元组的常用内置方法

元组则使用()创建，例如('hello','world')，元组是不可变序列，其主要表现为元组的元素不可以修改，但是元组的元素的元素可以被修改元组属于序列类型，可以在python解释器中使用dir(tuple)查看元组的内置方法

count

#返回某个元素在元组中出现的次数T.count(value) -> integer -- return number of occurrences of value

>>> t1=("hello","world",1,2,3,"linux",1,2,3)>>> t1.count(1)2>>> t1.count(3)2>>> t1.count("hello")1

index

#返回元素在元组中出现的第一个索引的值，元素不存在则报错T.index(value, [start, [stop]]) -> integer -- return first index of value.Raises ValueError if the value is not present.

>>> t1=("hello","world",1,2,3,"linux")>>> t1=("hello","world",1,2,3,"linux",1,2,3)>>> t1.count("hello")1>>> t1.index("linux")5>>> t1.index(3)4

字典的常用内置方法

字典属于映射类型，可以在python解释器中使用dir(dict)查看字典的内置方法

clear

#清除字典中所有的元素D.clear() -> None.  Remove all items from D.

>>> dic1={"k1":11,"k2":22,"k3":"hello","k4":"world"}>>> print(dic1){'k3': 'hello', 'k4': 'world', 'k2': 22, 'k1': 11}>>> dic1.clear()>>> print(dic1){}

copy

#浅复制D.copy() -> a shallow copy of D

>>> dic1={"k1":11,"k2":22,"k3":"hello","k4":"world"}>>> id(dic1)140300455000584>>> dic2=dic1.copy()>>> id(dic2)####140300455000648>>> print(dic2){'k2': 22, 'k4': 'world', 'k3': 'hello', 'k1': 11}

fromkeys(iterable, value=None, /)

#返回一个以迭代器中的每一个元素做健，值为None的字典Returns a new dict with keys from iterable and values equal to value.

>>> dic1={"k1":11,"k2":"hello"}>>> dic1.fromkeys([22,33,44,55]){33: None, 44: None, 22: None, 55: None}>>> print(dic1){'k2': 'hello', 'k1': 11}

get

#查询某个元素是否在字典中，即使不存在也不会报错D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None.

>>> dic1={'k3': None, 'k2': 'hello', 'k1': 11, 'k4': 'world'}>>> dic1.get("k3")>>> value1=dic1.get("k1")>>> print(value1)11>>> value2=dic1.get("k2")>>> print(value2)hello>>> value3=dic1.get("k5")>>> print(value3)None

items

#返回一个由每个键及对应的值构成的元组组成的列表D.items() -> a set-like object providing a view on D's items

>>> dic1={"k1":11,"k2":22,"k3":"hello","k4":"world"}>>> dic1.items()dict_items([('k3', 'hello'), ('k4', 'world'), ('k2', 22), ('k1', 11)])>>> type(dic1.items())
    

keys

#返回一个由字典所有的键构成的列表D.keys() -> a set-like object providing a view on D's keys

>>> dic1={"k1":11,"k2":22,"k3":"hello","k4":"world"}>>> dic1.keys()['k3', 'k2', 'k1', 'k4']

pop

#从字典中移除指定的键，返回这个键对应的值，如果键不存在则报错D.pop(k[,d]) -> v, remove specified key and return the corresponding value.If key is not found, d is returned if given, otherwise KeyError is raised

>>> dic1={"k1":11,"k2":22}>>> dic1.pop("k1")11>>> dic1.pop("k2")22

popitem

#从字典中移除一个键值对，并返回一个由所移除的键和值构成的元组，字典为空时，会报错D.popitem() -> (k, v), remove and return some (key, value) pair as a 2-tuple; but raise KeyError if D is empty.

>>> dic1={"k1":11,"k2":22}>>> dic1.popitem()('k2', 22)>>> dic1.popitem()('k1', 11)>>> dic1.popitem()Traceback (most recent call last):  File "
    
     ", line 1, in 
     
      KeyError: 'popitem(): dictionary is empty'
     
    

setdefault

#参数只有一个时，字典会增加一个键值对，键为这个参数，值默认为None；后接两个参数时，第一个参数为字典新增的键，第二个参数为新增的键对应的值D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D

>>> dic1={"k1":11,"k2":"hello"}>>> dic1.setdefault("k3")>>> print(dic1){'k3': None, 'k2': 'hello', 'k1': 11}>>> dic1.setdefault("k4","world")'world'>>> print(dic1){'k3': None, 'k2': 'hello', 'k1': 11, 'k4': 'world'}

update

#把一个字典参数合并入另一个字典，当两个字典的键有重复时，参数字典的键值会覆盖原始字典的键值D.update([E, ]**F) -> None.  Update D from dict/iterable E and F.If E is present and has a .keys() method, then does:  for k in E: D[k] = E[k]If E is present and lacks a .keys() method, then does:  for k, v in E: D[k] = vIn either case, this is followed by: for k in F:  D[k] = F[k]

>>> dic1={"k1":11,"k2":"hello"}>>> dic2={"k3":22,"k4":"world"}>>> dic1.update(dic2)>>> print(dic1){'k3': 22, 'k2': 'hello', 'k1': 11, 'k4': 'world'}>>> dic1={"k1":11,"k2":"hello"}>>> dic2={"k1":22,"k4":"world"}>>> dic1.update(dic2)>>> print(dic1){'k2': 'hello', 'k1': 22, 'k4': 'world'}

values

#返回一个由字典的所有的值构成的列表D.values() -> an object providing a view on D's values

>>> dic1={"k1":11,"k2":22,"k3":"hello","k4":"world"}>>> dic1.values()['hello', 22, 11, 'world']