import numpy as np
import pandas as pd
import time
 
sr = pd.Series([list('sdkajksdfdsaf') for _ in range(20000)])
sr.head(5)
 
>>>
0    [s, d, k, a, j, k, s, d, f, d, s, a, f]
1    [s, d, k, a, j, k, s, d, f, d, s, a, f]
2    [s, d, k, a, j, k, s, d, f, d, s, a, f]
 
3    [s, d, k, a, j, k, s, d, f, d, s, a, f]
4    [s, d, k, a, j, k, s, d, f, d, s, a, f]
dtype: object

start = time.time()
li1 = [i for k in sr for i in k]
time1 = time.time()
print('用生成式方法需要時間：', time1 - start)
 
li2 = np.sum(sr)
time2 = time.time()
print('用np.sum方法需要時間：', time2 - time1)
 
li3 
 
= sum(sr, [])
time3 = time.time()
print('用sum方法需要時間：', time3 - time2)
 
>>>
用生成式方法需要時間： 0.009999990463256836
用np.sum方法需要時間： 8.989910125732422
用sum方法需要時間： 8.979910373687744