Python 常用技巧(待续)

1. 计算运行时间

• time module

import time
start = time.time()
for i in range(10):
    print(i)
end = time.time()
end-start

• timeit module

def test():
    l = []
    for i in range(1000):
        l.append(i)
        
import timeit
t = timeit.Timer("test()", "from __main__ import test")
# from __main__ import test1 imports the function test1 
# from the __main__ namespace into the namespace that 
# timeit sets up for the timing experiment. 
print(t.timeit(number=1000), "milliseconds")

2. 修改文件名字

import os
# 改变当前工作目录
os.chdir('C:/Users/dingx/Documents/Python_tmp')
# 获取当前文件夹下文件名
files=os.listdir()
for filename in files:
	# 删除每个文件名的前三个字
    newname = filename[3:]
    # 改名字
    os.rename(filename , newname)  

**3. 内存释放 **

import gc
del a; #删除变量a
gc.collect(); #释放内存