比较字典推导式/dict()/通过键来构造的字典的速率 笔记

import time
dict1 = {‘a‘:1, ‘b‘:2, ‘c‘:3, ‘d‘:4}

start_time = time.time()
for i in range(100000):
d1 = {key:value for key,value in dict1.items() if value>2}
print(‘运行时间: {}‘.format(time.time() - start_time))
print(‘d1: {}‘.format(d1))

start_time = time.time()
for i in range(100000):
d2 = dict((key,value) for key,value in dict1.items() if value>2)
print(‘运行时间: {}‘.format(time.time() - start_time))
print(‘d2: {}‘.format(d2))

start_time = time.time()
for i in range(100000):
d3 = {key:dict1[key] for key in dict1.keys() if dict1[key]>2}
print(‘运行时间: {}‘.format(time.time() - start_time))
print(‘d3: {}‘.format(d3))

"""
D:\笔记\python电子书\Python3>python index.py
运行时间: 0.15999984741210938
d1: {‘c‘: 3, ‘d‘: 4}
运行时间: 0.2700002193450928
d2: {‘c‘: 3, ‘d‘: 4}
运行时间: 0.18000006675720215
d3: {‘c‘: 3, ‘d‘: 4}
"""