python基础2

• 集合

a.特点：具有无序性，单一性，不可重复性

b.用法：

　　b1.pop(随机删除)  remove(删除不存在元素会报错)  discard(删除不存在元素不会报错) 三者的区别

s={1,2,3,'Hacker_Teen','ugly','I'}
#i=0
#while i<len(s):
#    s.pop()
#    print(s)
#    i=i+1
#------------------------***-------------------
#s.remove('ugly')
#print(s)
#------------------------***-------------------
s.discard('3')
print(s)

　　b2.集合关系的交、并、差、交叉补集集的运算

python_study = {'wjc','xz','lz','wjc'}
C_study      = {'wjc','xz','gxq','cxf'}
py_1 = set(python_study)
C_1  = set(C_study)
print(py_1)
print(C_1)
#----------------取交集------------
#print(py_1.intersection(C_1))
#print((py_1)&(C_1))
#----------------取并集------------
#print(py_1.union(C_1))
#print(py_1|C_1)
#----------------取差集------------
#print(py_1.difference(C_1))
#print(py_1-C_1)
#----------------交差补集------------
#print(py_1.symmetric_difference(C_1))
#print(py_1^C_1)

　　b3.字符串格式化

#----------------字符串格式化------------
#self_introduce='I am %s,my age is %d'%('Hacker_Teen',21)
#print(self_introduce)
#print('percen%.2f'%98.67432)
#------------打印百分号------------------
#print('percen %.2f %%'%98.67432)
#-------------用字典传输-------------------
#self_introduce='I am %(name)s,my age is %(age)d'%({'name':'Hacker_Teen','age':21})
#print(self_introduce)
#----------------采用分隔符------------
print('wjc','xz','lz','gxq',sep=':')

　　b4.format的用法

#--------------format的用法---------------
li=['Hacker_Teen',21,'coding']
di={'name':'Hacker_Teen','age':21,'hobby':'coding'}
#print('I am {0}.Age is {1}.My hobby is {2}'.format('Hacker_Teen',21,'coding'))
#print('I am {name}.Age is {age}.My hobby is {hobby}'.format(name='Hacker_Teen',age=21,hobby='coding'))
#test1='I am {:s}.Age is {:d}.My hobby is {:s}'.format(*li)
#print(test1)
test2='I am {name}.Age is {age}.My hobby is {hobby}'.format(**di)
print(test2)

• 　　函数