python数据结构学习记录

python有三种数据结构：列表，字典和元组

1.元组

元组通过圆括号来表示，通过逗号来分隔元组中的内容。元组一旦建立就不可修改。下面是元组定义的举例。

#!/bin/python

#using_tuple



zoo = ("pig","cat","dog","lion")

new_zoo = ("bear","panda",zoo)



print "zoo : ",zoo

print "length of tuple zoo : ",len(zoo)

print "new_zoo : ",new_zoo

print "length of new_zoo : ",len(new_zoo)

print "zoo[0] is ",zoo[0]

print "zoo[3] is ",zoo[3]

print "new_zoo[0] is ",new_zoo[0]

print "new_zoo[1] is ",new_zoo[1]

print "new_zoo[2] is ",new_zoo[2]

print "new_zoo[2][2] is ",new_zoo[2][2]

输出结果如下：

zoo :  ('pig', 'cat', 'dog', 'lion')

length of tuple zoo :  4

new_zoo :  ('bear', 'panda', ('pig', 'cat', 'dog', 'lion'))

length of new_zoo :  3

zoo[0] is  pig

zoo[3] is  lion

new_zoo[0] is  bear

new_zoo[1] is  panda

new_zoo[2] is  ('pig', 'cat', 'dog', 'lion')

new_zoo[2][2] is  dog

 2.列表 list

列表用方括号表示，用逗号分割列表元素，列表是可变的数据结构，可以添加，删除和查找列表中的元素（例如购物表单）

列表的使用例子：

#!/bin/python

#using_list

mylist = ['go','python','lua','js']

print "length of list ",len(mylist)

for item in mylist:

        print item



print "add element"

mylist.append('ruby')

print "mylist : ",mylist



print "list[0] : ",mylist[0]

print "delete element"

del mylist[2]

print mylist

mylist.sort()

print mylist

输出：

length of list  4

go

python

lua

js

add element

mylist :  ['go', 'python', 'lua', 'js', 'ruby']

list[0] :  go

delete element

['go', 'python', 'js', 'ruby']

['go', 'js', 'python', 'ruby']

列表是小狮子的语言列表，列表中可以添加任何类型的对象，包括列表本身。方法append表示向列表中添加元素，sort表示对列表中元素排序，排序后再打印列表，列表已经改变。del语句表示删除列表中的元素。

3.字典

姓名（键）——电话号码（值）

键一般就是简单的对象，不可变。值可变。字典用大括号表示：{key1:value1,key2:value2} 

字典的操作举例：

#!/bin/python

#using_dict



mark = {'lion':'100',

        'dog':'98',

        'panda':'99',

        'pig':'96'}

print "mark is ",mark

print "mark[lion] ",mark['lion']

print "add element",

mark['cat'] = '93'

print mark

del mark['dog']

print mark

for name,num in mark.items():

        print 'name %s  num is %s' %(name,num)



if 'lion' in mark:

        print "lion num is ",mark['lion']

输出结果：

mark is  {'lion': '100', 'pig': '96', 'dog': '98', 'panda': '99'}

mark[lion]  100

add element {'lion': '100', 'pig': '96', 'dog': '98', 'cat': '93', 'panda': '99'}

{'lion': '100', 'pig': '96', 'cat': '93', 'panda': '99'}

name lion  num is 100

name pig  num is 96

name cat  num is 93

name panda  num is 99

lion num is  100

元组，列表，字典都是序列。序列的两个主要特点就是索引和切片，索引操作就是从序列中取得一个元素，切片是取得序列的一个部分。

序列操作举例：

#!/bin/python

mylist = ['a','b','c','d','e']

print "mylist ",mylist

print "mylist[0] ",mylist[0]

print "mylist[1] ",mylist[1]

print "mylist[-1] ",mylist[-1]

print "mylist[-2] ",mylist[-2]

print "mylist[0:3] ",mylist[0:3]

print "mylist[1:2] ",mylist[1:2]

print "mylist[:4] ",mylist[:4]

print "mylist[1:] ",mylist[1:]

输出结果：

mylist  ['a', 'b', 'c', 'd', 'e']

mylist[0]  a

mylist[1]  b

mylist[-1]  e

mylist[-2]  d

mylist[0:3]  ['a', 'b', 'c']

mylist[1:2]  ['b']

mylist[:4]  ['a', 'b', 'c', 'd']

mylist[1:]  ['b', 'c', 'd', 'e']

注意：序列的输出是左闭右开的，冒号前不写代表start_index，冒号后不写代表end_index