记忆化导致结果变慢
我正在创建一个记忆化的例子,主要是写一个函数来计算数组中元素的总和或平均值,并且和之前存储的结果进行比较,以便在结果已经存储的情况下直接取用。
另外,我想要设置一个条件,只有当函数的结果差别很大(比如低于5000)时,才会存储这个结果。
我用一个装饰器来实现这个功能,但使用装饰器的结果比不使用记忆化要慢一点,这让我觉得不太好。另外,装饰器的逻辑是否正确呢?
我的代码在下面:
import time
import random
from collections import OrderedDict
def memoize(f):
cache = {}
def g(*args):
sum_key_arr = sum(args[0])
print(sum_key_arr)
if sum_key_arr not in cache:
for key, value in OrderedDict(sorted(cache.items())).items():# key in dict cannot be an array so I use the sum of the array as the key
if abs(sum_key_arr - key) <= 5000:#threshold is great here so that all values are approximated!
#print('approximated')
return cache[key]
else:
#print('not approximated')
cache[sum_key_arr] = f(args[0],args[1])
return cache[sum_key_arr]
return g
@memoize
def aggregate(dict_list_arr,operation):
if operation == 'avg':
return sum(dict_list_arr) / len(list(dict_list_arr))
if operation == 'sum':
return sum(dict_list_arr)
return None
t = time.time()
for i in range(200,150000):
res = aggregate(list(range(i)),'avg')
elapsed = time.time() - t
print(res)
print(elapsed)
更新:我尝试引入一个ID键(用来捕捉列表的内容),现在使用字典作为输入,下面是我对代码所做的更改:
import time
import random
from collections import OrderedDict
def memoize(f):
cache = {}
def g(*args):
key_arr = list(args[0].keys())[0]
if key_arr not in cache:
for key, value in OrderedDict(sorted(cache.items())).items():# key in dict cannot be an array so I use the sum of the array as the key
if abs(int(key_arr) - int(key)) <= 5000:#threshold is great here so that all values are approximated!
print('approximated')
return cache[key]
else:
print('not approximated')
cache[key_arr] = f(args[0])
return cache[key_arr]
return g
#@memoize
def aggregate(dict_list_arr):
#if operation == 'avg':
return sum(list(dict_list_arr.values())[0]) / len(list(dict_list_arr.values())[0])
# if operation == 'sum':
# return sum(dict_list_arr)
# None
t = time.time()
for i in range(200,15000):
res = aggregate({str(1+i):list(range(i))})
elapsed = time.time() - t
print(res)
print(elapsed)
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