用map来处理字符串列表

用map来处理字符串列表,把列表中所有水果都变成juice,比方apple_juice

  fruits=['apple','orange','mango','watermelon']

fruits=['apple','orange','mango','watermelon']
def func(fruit):
return fruit+'_juice'
f = map(func,fruits)
print(list(f))

python学习日记(内置、匿名函数练习题)-LMLPHP

匿名函数实现:

fruits=['apple','orange','mango','watermelon']
print(list(map(lambda fruit:fruit+'_juice',fruits)))

用filter函数处理数字列表

用filter函数处理数字列表,将列表中所有的偶数筛选出来

  num = [1,3,5,6,7,8]

num = [1,3,5,6,7,8]
def func(x):
return x%2 == 0
l = filter(func,num)
print(list(l))

python学习日记(内置、匿名函数练习题)-LMLPHP

匿名函数实现:

num = [1,3,5,6,7,8]
print(list(filter(lambda x:x%2 == 0,num)))
# print(list(filter(lambda x:True if x%2 == 0 else False,num)))

随意写一个20行以上的文件...

如题

随意写一个20行以上的文件
运行程序,先将内容读到内存中,用列表存储;
接收用户输入页码,每页5条,仅输出当页的内容。

简单实现:

with open('file',encoding='utf-8') as f:
line = f.readlines()
pages,left = divmod(len(line),5)#pages-->拥有五行的总页数,left-->余下一页的行数
page_num = int(input('请输入页码(整数):'))
if page_num <= 0 or page_num > pages+1:
print('页码不存在')
elif page_num > 0 and page_num <= pages:
for i in range(5):
print(line[(page_num-1)*5+i].strip())
else:
for i in range(left):
print(line[(page_num - 1) * 5 + i].strip())

python学习日记(内置、匿名函数练习题)-LMLPHP   python学习日记(内置、匿名函数练习题)-LMLPHP

升级版(交互式)

with open('file',encoding='utf-8') as f:
line = f.readlines()
pages,left = divmod(len(line),5)#pages-->拥有五行的总页数,left-->余下一页的行数
while True:
page_num = input('请输入页码(Q退出case-insensitive):')
if page_num.lower() == 'q':
print('阅读结束')
break
else:
if page_num.isdigit():
page_num = int(page_num)
if page_num <= 0 or page_num > pages + 1:
print('页码不存在')
print('请重新输入')
continue
elif page_num > 0 and page_num <= pages:
for i in range(5):
print(line[(page_num-1)*5+i].strip())
continue
else:
for i in range(left):
print(line[(page_num - 1) * 5 + i].strip())
continue
else:
print('请输入整数')
continue

python学习日记(内置、匿名函数练习题)-LMLPHP

如下,每个小字典的name对应股票名字...

如题

如下,每个小字典的name对应股票名字,shares对应多少股,price对应股票的价格

#如下,每个小字典的name对应股票名字,shares对应多少股,price对应股票的价格
portfolio = [
{'name': 'IBM', 'shares': 100, 'price': 91.1},
{'name': 'AAPL', 'shares': 50, 'price': 543.22},
{'name': 'FB', 'shares': 200, 'price': 21.09},
{'name': 'HPQ', 'shares': 35, 'price': 31.75},
{'name': 'YHOO', 'shares': 45, 'price': 16.35},
{'name': 'ACME', 'shares': 75, 'price': 115.65}]
# 1.计算购买每支股票的总价
# 2.用filter过滤出,单价大于100的股票有哪些

1.计算购买每支股票的总价

def func(dic):
return {dic['name']:dic['shares']*dic['price']}
r = map(func,portfolio)
print(list(r))

python学习日记(内置、匿名函数练习题)-LMLPHP

  匿名函数改进

print(list(map(lambda dic:{dic['name']:round(dic['shares']*dic['price'],2)},portfolio)))

python学习日记(内置、匿名函数练习题)-LMLPHP

2.用filter过滤出,单价大于100的股票有哪些

def func(dic):
return dic['price'] > 100
r = filter(func,portfolio)
print(list(r))

python学习日记(内置、匿名函数练习题)-LMLPHP

  匿名函数实现

print(list(filter(lambda dic:dic['price'] > 100,portfolio)))

pass

04-21 03:45