每天CookBook之Python-004

使用lambda支持heapq获取复杂对象集合的最大N项和最小N项

# -*- coding: utf-8 -*-
mport heapq

nums = [1, 8, 2, 23, 7, -4, 18, 23, 42, 37, 2]
print heapq.nlargest(3, nums)
print heapq.nsmallest(3, nums)

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},
]

print heapq.nsmallest(3, portfolio, key=lambda s:s['price'])
expensive = heapq.nlargest(3, portfolio, key=lambda s:s['price'])

out

[{'price': 16.35, 'name': 'YHOO', 'shares': 45}, {'price': 21.09, 'name': 'FB', 'shares': 200}, {'price': 31.75, 'name': 'HPQ', 'shares': 35}]
[{'price': 543.22, 'name': 'AAPL', 'shares': 50}, {'price': 115.65, 'name': 'ACME', 'shares': 75}, {'price': 91.1, 'name': 'IBM', 'shares': 100}]