基础数据类型-list

序列是python中的基础数据结构，序列里每一个元素都有一个下标，从0开始，依次递增.

list,tuple,dictionary是使用最频繁的三类数据结构。

（1）序列都有的方法包括：索引，切片，检查成员，加，乘：

 #!/usr/bin/env python
 # -*- coding: UTF-8 -*-
 #索引
 list_name = ['Paul', 'John', 'James']
 print(list_name[1])

 #切片
 list_number = [1, 1, 2, 3, 4, 5]
 print(list_number[1:5])

 #检查成员
 if 'Joshua' in list_name:
     print("Joshua is in list_name")
 else:
     print("Joshua is not in list_name")

 #加
 print(list_name + list_number)

 #乘
 print(list_name * 2)

Code

 John
 [1, 2, 3, 4]
 Joshua is not in list_name
 ['Paul', 'John', 'James', 1, 1, 2, 3, 4, 5]
 ['Paul', 'John', 'James', 'Paul', 'John', 'James']

Result

(2)遍历列表：

 #遍历列表
 for number in list_number:
     print(number)

Code

(3)list的函数有len(),max(),min(),list()

 #函数
 print(len(list_number))
 print(max(list_number))
 print(min(list_number))
 tuple_number = (1, 3, 5, 7)
 print(type(tuple_number), type(list(tuple_number)))#list()强制将序列转化为list类型

Code

 6
 5
 1
 <class 'tuple'> <class 'list'>

Result

(4)list的常用方法有

-append(), extend(),insert();

 #append(), extend(),insert();
 list_number = [1, 1, 2, 3, 4, 5]
 list_number.append(7) #在列表末尾添加新的对象
 print(list_number)
 list_number.extend([10, 11, 12]) #在列表末尾一次性追加另一个序列中的多个值（用新列表扩展原来的列表）
 print(list_number)
 list_number.insert(1, 99) #list.insert(index, obj)将对象插入列表中index位置
 print(list_number)

Code

 [1, 1, 2, 3, 4, 5, 7]
 [1, 1, 2, 3, 4, 5, 7, 10, 11, 12]
 [1, 99, 1, 2, 3, 4, 5, 7, 10, 11, 12]

Result

-remove(),pop(),clear();

 #remove(),pop(),clear();
 list_number = [1, 1, 2, 3, 4, 5]
 list_number.remove(1)#移除列表中某个值的第一个匹配项
 print(list_number)
 pop_number = list_number.pop(4)#list.pop(obj=list[-1]) 移除列表中的索引位置元素（默认最后一个元素），并且返回该元素的值
 print("pop number:", pop_number)
 print(list_number)
 list_number.clear()#清空列表
 print(list_number)

Code

 [1, 2, 3, 4, 5]
 pop number: 5
 [1, 2, 3, 4]
 []

Result

-sort(),reverse();

 #sort(),reverse();
 list_number = [4, 2, 5, 7, 1, 3]
 print(list_number)
 list_number.sort() #对原列表进行排序
 print(list_number)
 list_number.reverse() #反向原列表中元素
 print(list_number)

Code

 [4, 2, 5, 7, 1, 3]
 [1, 2, 3, 4, 5, 7]
 [7, 5, 4, 3, 2, 1]

Result

-count(),index(),copy()

 #count(),index(),copy()
 list_number = [1, 1, 2, 2, 2, 3, 3, 3, 3]
 print(list_number.count(3)) #统计某个元素在列表中出现的次数
 print(list_number.index(2)) #从列表中找出某个值第一个匹配项的索引位置
 print("address of list_number:", id(list_number))
 copy_list_number = list_number.copy() #复制列表
 print(copy_list_number)
 print("address of copy_list_number:", id(copy_list_number))

Code

 4
 2
 address of list_number: 35406832
 [1, 1, 2, 2, 2, 3, 3, 3, 3]
 address of copy_list_number: 35421720

Result

最后来看下list类的定义：

 class list(object):
     """
     list() -> new empty list
     list(iterable) -> new list initialized from iterable's items
     """
     def append(self, p_object): # real signature unknown; restored from __doc__
         """ L.append(object) -- append object to end """
         pass

     def count(self, value): # real signature unknown; restored from __doc__
         """ L.count(value) -> integer -- return number of occurrences of value """
         return 0

     def extend(self, iterable): # real signature unknown; restored from __doc__
         """ L.extend(iterable) -- extend list by appending elements from the iterable """
         pass

     def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
         """
         L.index(value, [start, [stop]]) -> integer -- return first index of value.
         Raises ValueError if the value is not present.
         """
         return 0

     def insert(self, index, p_object): # real signature unknown; restored from __doc__
         """ L.insert(index, object) -- insert object before index """
         pass

     def pop(self, index=None): # real signature unknown; restored from __doc__
         """
         L.pop([index]) -> item -- remove and return item at index (default last).
         Raises IndexError if list is empty or index is out of range.
         """
         pass

     def remove(self, value): # real signature unknown; restored from __doc__
         """
         L.remove(value) -- remove first occurrence of value.
         Raises ValueError if the value is not present.
         """
         pass

     def reverse(self): # real signature unknown; restored from __doc__
         """ L.reverse() -- reverse *IN PLACE* """
         pass

     def sort(self, cmp=None, key=None, reverse=False): # real signature unknown; restored from __doc__
         """
         L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*;
         cmp(x, y) -> -1, 0, 1
         """
         pass

Class List