1.Python进阶-Python变量与数据类型

柔光的暖阳◎ 2022-06-16 10:20 152阅读 0赞

**1.Python变量与数据类型**

\#测试raw字符串和多行字符串

#测试raw字符串和多行字符串
    
    #测试raw字符串
    r '\(~_~)/ \(~_~)/'
    print r
    
    #测试多行字符串
    print '''
    python is created by "Guido",
    it is free and easy to learn,
    let's start learn python!
    '''

# -*- coding: utf-8 -*-
    #（add this instruction to avoid failure to recognize the Chinese）
    #and the instruction must be added in the first row.
    #1.test Unicode
    a=u'中国'
    print a
    
    b='美国\n'
    print b #then the program can print letters but not
            #the right leters without adding 'u'
    
    #2.test Unicode and multiply rows
    print ur'''静夜思
    床前明月光，
    疑是地上霜；
    举头望明月，
    低头思故乡。
    '''

**2.数据结构\_list,tuple,dict,set**

**测试list:**

# -*- coding :utf-8 -*-
    #function:test list in Python
    a=['wuhan','shiyan','shanghai'] #you can add or delete letters freely
    b=['jinjian',25,True]
    print a
    
    #empty list
    c_list=[]

#function:visit the list defined
    
    person=['jinjian','liyang','luodan']
    print person[0]
    
    score1=[10,12,9]
    print score1[1]
    
    #function:visit the list from the opposite direction
    L=['jinjian','zhangshan','lisi']
    print L[0]
    print L[-1]

#function :add elements to the list
    student1=['zhangshan','lisi','liyang']
    
    student1.append('luodan')
    print student1
    #use append to add an element to the end of the list
    #use insert to add an element to anyplace you want to the list
    student1.insert(1,'wangzi')
    print student1
    
    #function:delete the element from the list
    a1=['zhangshan','liyang','lisi']
    a1.pop() #delete the last element from the list
    print a1
    a1.append('lisi')
    print a1
    
    a1.pop(1)
    print a1

**测试tuple：**

# -*- coding: utf-8 -*- 
    #function : define tuple
    tuple1=('zhangshan','lisi','liyang')
    print u'''tuple 是元组，一旦定义一个tuple后，
           其元素数量和元素内容均无法改变。
           无法向元组中加入或删除元素，也不能赋值成别的元素，
           只能访问元素'''
    
    print u'''创建tuple和list的唯一不同是（）和[]
             '''
    print tuple1[1]
    print tuple1[-1]
    
    #to define a tuple with single element
    tuple2=(2,)
    print tuple2
    
    tuple3=(2)
    print tuple3
    
    #-*- coding :utf-8 -*-
    #function :to define a changeable tuple
    
    tuple1=(1,2,3,4)  #unchangeable
    tuple2=(1,2,['a','b'])  #changeable
    L=tuple2[2]
    L[0]='c'
    L[1]='d'
    print tuple1
    print tuple2

**测试dict：**

# -*- coding: cp936 -*-
    #-*- coding:utf-8 -*-
    #function:test dict
    #dict的特点：(1)dict是按照key(键）查找的，因此key不能重复
    #（2）存储的key-value是没有顺序的，即打印的顺序不一定是我们创建时的
    #顺序；这说明dict内部是无序的，因此不能用dict存储有序的集合。
    #（3）在dict中，作为key的元素必须不能改变
    
    #1.define a dict
    stu={'zhangshan':89,
         'lisi':59,
         'liyang':94}
    b=len(stu) #calculate the length of stu
    print b
    stu2={'123':[1,2,3],
          ('jinjian','student'):['beijing',25],
          007:100} #圆括号内的值是不可变的，方括号内的值是可变的
    
    #2.visit the dict
    print stu['zhangshan']
    print stu
    print len(stu2)
    print stu2[('jinjian','student')]
    
    #3.refresh the dict
    stu['zhaodashi']=78
    print stu
    
    #iterator the dict
    print 'xunhuan'
    for key1 in stu:
          print key1,stu[key1]
    print 'finish'

**测试set：**

# -*- coding: cp936 -*-
    #-*- coding:utf-8 -*-
    #测试set类型
    #set持有一系列元素，和list很像，但是set的元素没有重复，而且
    #是无序的，这个和dict很像
    
    #1.create or define a set
    #创建set的方法是调用set函数，并传入一个list,list的元素将作为set的元素
    s=set(['jim','mike','lucy'])
    print s #打印的结果顺序可能和创建时不一致
    
    #2.set类型能自动剔除重复元素
    s2=set(['a','c','w','f','c'])
    print s2
    print len(s2)
    
    #3.visit the set
    x=('zhangshan' in s)
    y=('jim' in s)
    print x,y  #output False True
    
    #4.characters of set
    #(1)set内部结构和dict很像，唯一区别是不能存储value
    #(2)set存储的元素和dict的key一样，必须是不变的对象,因此任何可变对象都不能放在set中
    weekdays=set(['Monday','Tuesday','Wednesday','Thursday','Friday'])
    x='Saturday'
    if x in weekdays:
          print 'input ok'
    else:
          print 'input error'
    
    #5.iterator the set
    print '开始遍历测试'
    s3=set([('tom',12),('lily',25),('green',18)])
    for x in s3:
          print x
    
    #6.refresh the set, use add() or remove()
    s2.add(12)
    s2.add('k')
    s3.add((12,'jinjian'))
    print s2
    print s3
    s3.remove(('tom',12))
    print s3