004.01 不同 Python 数据类型的搜寻
建檔日期: 2019/12/08
更新日期: None
相关软件信息:
Win 10 | Python 3.7.2 |
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主题: 004.01 不同Python数据类型的搜寻
最近在作资料搜索比对的案子的时候, 发现大量的数据在搜索比对时, 速度变的非常慢, 慢到完全无法接受, 我想要的是’立即’有结果, 结果却是要等好几小时, 晕 ! 虽然以Python来说, 肯定比不上C或Assembly语言, 但是还是要想办法提升一下速度. 以下是在一万笔数据中, 找一万笔数据的各种方法以及所需的时间, 虽然最后一个方法index_list_sort()
, 速度快了多, 但是我还是觉得不够快, 而且这里还只是整数的搜索, 如果是字符串呢? 如果是副字符串呢? 各位如果有更好的方法, 也请提示, 谢谢 !
结果:
0:00:04.734338 : index_sequence
0:00:01.139984 : index_list
0:00:00.330116 : index_np
0:00:00.233343 : index_np_sort
0:00:00.223401 : index_dict
0:00:00.213462 : index_set
0:00:00.007977 : index_list_sort
代码:
from datetime import datetime
import numpy as np
import bisect
import time
import random
import inspect
import copy
size = 10000
value = size-1
db = random.sample(range(size), size)
db_sort = copy.deepcopy(db)
db_sort.sort()
db_set = set(db)
db_dict = {db[i]:i for i in range(size)}
db_np = np.array(db)
value = [i for i in range(size)]
def call(func):
# Call function and calculate execution time, then print duration and function name
start_time = datetime.now()
func()
print(datetime.now() - start_time,':',func.__name__)
def do_something():
# Do something here, it may get duration different when multi-loop method used
for i in range(1000):
pass
def index_sequence():
# List unsort and just by Python without any method used or built-in function.
for i in range(size):
for j in range(size):
if value[j] == db[i]:
index = j
do_something()
break
def index_list():
# Unsorted list, use list.index()
for i in range(size):
try:
index = db.index(value[i])
except:
index = -1
if index >= 0:
do_something()
def index_np():
# By using numpy and np(where)
for i in range(size):
result = np.where(db_np==value[i])
if len(result[0])!=0:
do_something()
def index_np_sort():
# By using numpy and sorted numpy array
for i in range(size):
result = np.searchsorted(db_np, value[i])
if result != size:
do_something()
def index_list_sort():
# By using bisect library
for i in range(size):
index = bisect.bisect_left(db, value[i])
if index < size-1 and value[index]==db[index]:
do_something()
def index_set():
# Set serach
for i in range(size):
if value[i] in db_set:
do_something()
def index_dict():
# Dictionary search
for i in range(size):
try:
index = db_dict[value[i]]
except:
index = -1
if index >= 0:
do_something()
# Test execution time
call(index_sequence)
call(index_list)
call(index_np)
call(index_np_sort)
call(index_dict)
call(index_set)
call(index_list_sort)
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