转换并同时计算数据

 1. 计算平方和

nums = [1, 2, 3, 4, 5]
s = sum(x * x for x in nums)
print(s) #55

2. 查找文件后缀名

import os
files = os.listdir('D:\xxx\xxx\xxx')
if any(name.endswith('.py') for name in files):
    print('there is python ！')
else: 
    print('sorry,no python!')

3. 元组--->字符串

s = ('ACME', 50, 123.45)
print(','.join(str(x) for x in s)) #ACME,50,123.45

4. 查找数据

portfolio = [
    {'name':'GOOG', 'shares': 50},
    {'name':'YHOO', 'shares': 75},
    {'name':'AOL', 'shares': 20},
    {'name':'SCOX', 'shares': 65}
]
min_shares = min(s['shares'] for s in portfolio)
print(min_shares) #20
min_shares1 = min(portfolio,key = lambda s : s['shares'])
print(min_shares1) #{'name': 'AOL', 'shares': 20}
max_shares = max(portfolio, key=lambda s: s['shares'])
print(max_shares) #{'name': 'YHOO', 'shares': 75}