How to compare two lists in python

Through continuous testing, we found that python can efficiently and quickly compare the differences between two lists. It can operate with the help of the set operation provided by python set(). This method is very efficient.

In the Java language, method 1 of the following methods is more efficient and faster than method 2 (set operation). This can be regarded as a little difference between the similarities between the two languages.

The code is as follows:

#-*- coding:utf-8 -*-
import time

#方法1:
def getDiff1(arr1,arr2):
    start_time = time.time()
    print('1_start:',start_time)
    arr_more1 = []
    arr_more2 = []
    dic_result = {}

    for str_1 in arr1:
        dic_result[str(str_1)] = 1

    for str_2 in arr2:
        if dic_result.get(str(str_2)):
            dic_result[str(str_2)] = 2
        else:
            arr_more2.append(str_2)

    for key,val in dic_result.items():
        if val == 1:
            arr_more1.append(key)

    print('arr1比arr2多的内容为:',len(arr_more1))
    print('arr2比arr1多的内容为:',len(arr_more2))

    end_time = time.time()
    print('1_end:',end_time)
    print('方法1_比对用时为',end_time-start_time)


#方法2:使用集合运算:
def getDiff2(arr1,arr2):
    start_time = time.time()
    print('2_start:',start_time)
    set_1 = ()
    set_2 = ()

    #将列表转换为集合set()
    set_1 = set(arr1)
    set_2 = set(arr2)

    set_more1 = ()
    set_more2 = ()

    #集合运算
    set_1_2 = set_1 & set_2
    set_more1 = set_1 -set_1_2
    set_more2 = set_2 -set_1_2

    print('arr1比arr2多的内容为:',len(set_more1))
    print('arr2比arr1多的内容为:',len(set_more2))

    end_time = time.time()
    print('2_end:',end_time)
    print('方法2_比对用时为',end_time-start_time)

#测试

# 初始化500w条数据数据
arr1 = []
arr2 = []
i = 0
while(True):
    arr1.append(i * 2)
    arr2.append(i * 3)
    i += 1
    if i > 5000000:
        break

print('arr1的长度为:',len(arr1))
print('arr2的长度为:',len(arr2))
print('+'*30)
getDiff1(arr1,arr2)
print('-'*30)
getDiff2(arr1,arr2)

Running results:

Learn in the Python tutorial column!

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