python小练习

假如有列表：

books = [
　　{"name":"C#", "price":23.7, "store":"amaing"},
　　{"name":"ASP.NET", "price":44.5, "store":"amaing"},
　　{"name":"C#", "price":24.7, "store":"dd"},
　　{"name":"ASP.NET", "price":45.7, "store":"dd"},
　　{"name":"C#", "price":26.7, "store":"xh"},
　　{"name":"ASP.NET", "price":55.7, "store":"xh"},
]

1 求《ASP.NET》价格最便宜的店：
2 求在新华书店购买两本书一样一本要花的钱：
3 求列表中有那几本书：
4 列表里的书都打5折：
5 《C#》的平均价格：
6 求每本书的平均价格：

1.
min=0
for i in books:
    if(i['name']=='ASP.NET'):
        if min<i['price']:
            #global  min,ri
            min=i['price']
            ri=i;

print ri

2.

price=0
for b in books:
    if(b['store']=='xh'):
        price+=b['price']

print price

3.
bname =[]
for b in books:
    bname.append(b['name'])  ##不能用bname+=

bname=list(set(bname))
print bname

4.
books2=[]
price=0
bookNum=0
for b in books:
    b['price']=b['price']/2
    books2.append(b)

print books2

5.
price=0
bookNum=0
for b in books:
    if(b['name']=='C#'):
        price+=b['price']
        bookNum=bookNum+1

print price*1.0/bookNum

6.
nameNum={}
namePrice={}
books2=list(set())
str=''
for a in books:
    if a['name'] in nameNum:
        str=a['name']
        nameNum[str]=nameNum[str]+1
        namePrice[str]=namePrice[str]+a['price']
    else:
        str=a['name']
        nameNum[str]=1
        namePrice[str]=a['price']

        
print nameNum
print namePrice

nameAvg={}
for a in nameNum:
    str=a
    temp=namePrice[str]*1.0/nameNum[str]
    nameAvg[str]=temp

print nameAvg