python 装饰器/Cprofile计算函数执行时间
用简单的堆排序来查看这些工具
今天先看一些内建工具
自己写一个装饰器
注释掉的部分是将尾递归省略掉的方法，理论上会提升效率，我用来做比较的
wujingcideMacBook-Pro:test wujingci$ cat dp.py
# encoding: utf-8
import random
from functools import wraps
import time
def timefn(function):
@wraps(function)
def count_time(*args, **kwargs):
t1 = time.time()
result = function(*args, **kwargs)
t2 = time.time()
print (function.func_name + ' took ' + str(t2-t1) + ' seconds')
return result
return count_time
heap_size = 0
LEFT = lambda i: 2*i+1
RIGHT = lambda i: 2*i+2
# 维护最大堆
def HEAPIFY(A, i):
l, r = LEFT(i), RIGHT(i)
largest = l if l < heap_size and A[l] > A[i] else i # 最小堆则改为 A[l] < A[i]
largest = r if r < heap_size and A[r] > A[largest] else largest # 最小堆则改为A[r] < A[largest]
if i != largest:
A[i], A[largest] = A[largest], A[i]
HEAPIFY(A,largest)
# 去除尾递归
#def HEAPIFY(A, i):
# while True:
# l, r = LEFT(i), RIGHT(i)
# largest = l if l < heap_size and A[l] > A[i] else i
# largest = r if r < heap_size and A[r] > A[largest] else largest
# if i == largest: break
# A[i], A[largest] = A[largest], A[i]
# i = largest
# 构建最大堆
def BUILD_MAX_HEAP(A):
global heap_size
heap_size = len(A)
for i in range(len(A)//2-1,-1,-1):
HEAPIFY(A,i)
# 堆排序
def HEAPSORT(A):
global heap_size
BUILD_MAX_HEAP(A)
for i in range(len(A)-1,-1,-1):
A[i], A[0] = A[0], A[i]
heap_size -= 1
HEAPIFY(A,0)
@timefn
def main():
a = []
for i in range(10000):
a.append(random.randint(0,100000))
print 'before'
print a
print '\nafter'
HEAPSORT(a)
print a
if __name__ == "__main__":
main()跑一下，运行了main took 0.189006090164 seconds
这个是有差异化的，不过我们可以试着去掉尾递归main took 0.150513887405 seconds
貌似快一点，不过这说明不了什么，因为随机产生的数列要进行的元素交换次数不一样
用unix的time命令
将装饰器注释掉
time -p python dp.py
real 0.14
user 0.10
sys 0.01
用cprofile
428031 function calls (313707 primitive calls) in 0.183 seconds
Ordered by: cumulative time
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.001 0.001 0.183 0.183 dp.py:2(<module>)
1 0.017 0.017 0.175 0.175 dp.py:52(main)
1 0.004 0.004 0.143 0.143 dp.py:43(HEAPSORT)
129324/15000 0.109 0.000 0.138 0.000 dp.py:20(HEAPIFY)
129324 0.015 0.000 0.015 0.000 dp.py:17(<lambda>)
129324 0.014 0.000 0.014 0.000 dp.py:18(<lambda>)
10000 0.003 0.000 0.014 0.000 random.py:238(randint)
1 0.001 0.001 0.012 0.012 dp.py:37(BUILD_MAX_HEAP)
10000 0.010 0.000 0.010 0.000 random.py:175(randrange)
1 0.003 0.003 0.007 0.007 random.py:40(<module>)
1 0.003 0.003 0.003 0.003 hashlib.py:56(<module>)
10000 0.001 0.000 0.001 0.000 {method 'append' of 'list' objects}
1 0.000 0.000 0.001 0.001 random.py:91(__init__)
1 0.000 0.000 0.001 0.001 random.py:100(seed)
10000 0.001 0.000 0.001 0.000 {method 'random' of '_random.Random' objects}
1 0.000 0.000 0.000 0.000 {function seed at 0x1061a8ed8}
3 0.000 0.000 0.000 0.000 {range}
1 0.000 0.000 0.000 0.000 {posix.urandom}
6 0.000 0.000 0.000 0.000 hashlib.py:100(__get_openssl_constructor)
1 0.000 0.000 0.000 0.000 random.py:72(Random)
1 0.000 0.000 0.000 0.000 {binascii.hexlify}
2 0.000 0.000 0.000 0.000 {math.log}
1 0.000 0.000 0.000 0.000 {math.exp}
1 0.000 0.000 0.000 0.000 __future__.py:48(<module>)
6 0.000 0.000 0.000 0.000 {getattr}
1 0.000 0.000 0.000 0.000 {method 'union' of 'set' objects}
1 0.000 0.000 0.000 0.000 random.py:655(WichmannHill)
1 0.000 0.000 0.000 0.000 random.py:805(SystemRandom)
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_md5}
3 0.000 0.000 0.000 0.000 {len}
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha224}
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha256}
7 0.000 0.000 0.000 0.000 __future__.py:75(__init__)
1 0.000 0.000 0.000 0.000 {math.sqrt}
1 0.000 0.000 0.000 0.000 __future__.py:74(_Feature)
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha1}
6 0.000 0.000 0.000 0.000 {globals}
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha512}
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha384}
1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}去除尾递归的结果
313689 function calls in 0.153 seconds
Ordered by: cumulative time
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.001 0.001 0.153 0.153 dp.py:2(<module>)
1 0.016 0.016 0.144 0.144 dp.py:52(main)
1 0.003 0.003 0.114 0.114 dp.py:43(HEAPSORT)
15000 0.081 0.000 0.110 0.000 dp.py:27(HEAPIFY)
129315 0.015 0.000 0.015 0.000 dp.py:17(<lambda>)
129315 0.014 0.000 0.014 0.000 dp.py:18(<lambda>)
10000 0.003 0.000 0.013 0.000 random.py:238(randint)
1 0.001 0.001 0.010 0.010 dp.py:37(BUILD_MAX_HEAP)
10000 0.009 0.000 0.010 0.000 random.py:175(randrange)
1 0.004 0.004 0.008 0.008 random.py:40(<module>)
1 0.003 0.003 0.003 0.003 hashlib.py:56(<module>)
1 0.000 0.000 0.001 0.001 random.py:91(__init__)
1 0.000 0.000 0.001 0.001 random.py:100(seed)
10000 0.001 0.000 0.001 0.000 {method 'append' of 'list' objects}
10000 0.001 0.000 0.001 0.000 {method 'random' of '_random.Random' objects}
1 0.001 0.001 0.001 0.001 {function seed at 0x1085b5ed8}
3 0.000 0.000 0.000 0.000 {range}
1 0.000 0.000 0.000 0.000 {posix.urandom}
1 0.000 0.000 0.000 0.000 {binascii.hexlify}
6 0.000 0.000 0.000 0.000 hashlib.py:100(__get_openssl_constructor)
1 0.000 0.000 0.000 0.000 __future__.py:48(<module>)
2 0.000 0.000 0.000 0.000 {math.log}
1 0.000 0.000 0.000 0.000 random.py:72(Random)
1 0.000 0.000 0.000 0.000 {math.exp}
6 0.000 0.000 0.000 0.000 {getattr}
1 0.000 0.000 0.000 0.000 {method 'union' of 'set' objects}
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_md5}
7 0.000 0.000 0.000 0.000 __future__.py:75(__init__)
1 0.000 0.000 0.000 0.000 random.py:655(WichmannHill)
3 0.000 0.000 0.000 0.000 {len}
1 0.000 0.000 0.000 0.000 random.py:805(SystemRandom)
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha512}
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha256}
1 0.000 0.000 0.000 0.000 {math.sqrt}
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha384}
1 0.000 0.000 0.000 0.000 __future__.py:74(_Feature)
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha1}
1 0.000 0.000 0.000 0.000 {_hashlib.openssl_sha224}
1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}
6 0.000 0.000 0.000 0.000 {globals}
1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}调用的函数次数要少一些