Python 笔记

#生成式
prices = {
    'meat' : 543.2,
    'duck' : 123.56,
    'dog' : 45.67,
    'horse' : 78.55,
    'miao' : 123.55
}
price = {key : value for key, value in prices.items() if value > 100}
print(price)

#嵌套的列表
names = ['小明', '小红', '小王']
courses = ['英语', '数学', '生物', '物理']
chart = [[None]*len(courses) for _ in range(len(names))]
for low, name in enumerate(names):
    for lol, course in enumerate(courses):
        chart[low][lol] = float(input(f'{name}的{course}成绩为：'))
print(chart)

#heapq模块(堆排列)
import heapq
list1 = [44, 23, 56, 34, 33, 55, 234, 45, 24, 46]
list2 = [
{'name' : '小明', 'shares':45, 'price':234},
{'name' : '小红', 'shares':55, 'price':567},
{'name' : '小王', 'shares':89, 'price':678},
{'name' : '小玉', 'shares':67, 'price':980},
]
print(heapq.nlargest(3, list1))
print(heapq.nsmallest(3, list1))
print(heapq.nlargest(2, list2, key = lambda x :x['shares']))
print(heapq.nlargest(2, list2, key=lambda x:x['price']))

#itertools模块(迭代工具)
import itertools
#产生abcd全排列
print(itertools.permutations('abcd'))
#产生abcde的五选三组合
print(itertools.combinations('abcde', 5))
#产生abcd和123的笛卡尔积
print(itertools.product('abcd', '123'))
#产生abc的无限序列
print(itertools.cycle(('a','b','c')))