我真的希望你能帮助我。
我有以下代码，它完全可以按照我的要求工作。它需要包含大量子域的域，并将其规范化为仅主机名+ TLD。
但是，它非常慢。我听说过关于熊猫数据帧的矢量化的信息，但是我必须承认，我对此并不十分了解，也找不到任何有人在使用if，else语句的示例。
如果任何人都可以建议我如何使它更有效/并举例说明如何将if，elseif等与向量化一起使用，那就太好了！
import pandas as pd
import time
#import file into dataframe
start = time.time()
path = "Desktop/dom1.csv"
df = pd.read_csv(path, delimiter=',', header='infer', encoding = "ISO-8859-1")
#strip out all ---- values
df2 = df[((df['domain'] != '----'))]
#extract only 2 columns from dataframe
df3 = df2[['domain', 'web.optimisedsize']]
#define tld and cdn lookup lists
tld = ['co.uk', 'com', 'org', 'gov.uk', 'co', 'net', 'news', 'it', 'in' 'es', 'tw', 'pe', 'io', 'ca', 'cat', 'com.au',
'com.ar', 'com.mt', 'com.co', 'ws', 'to', 'es', 'de', 'us', 'br', 'im', 'gr', 'cc', 'cn', 'org.uk', 'me', 'ovh', 'be',
'tv', 'tech', '..', 'life', 'com.mx', 'pl', 'uk', 'ru', 'cz', 'st', 'info', 'mobi', 'today', 'eu', 'fi', 'jp', 'life',
'1', '2', '3', '4', '5', '6', '7', '8', '9', '0', 'earth', 'ninja', 'ie', 'im', 'ai', 'at', 'ch', 'ly', 'market', 'click',
'fr', 'nl', 'se']
cdns = ['akamai', 'maxcdn', 'cloudflare']
#iterate through each row of the datafrme and split each domain at the dot
for row in df2.itertuples():
index = df3.domain.str.split('.').tolist()
cleandomain = []
#iterate through each of the split domains
for x in index:
#if it isn't a string, then print the value directly in the cleandomain list
if not isinstance(x, str):
cleandomain.append(str(x))
#if it's a string that encapsulates numbers, then it's an IP
elif str(x)[-1].isnumeric():
try:
cleandomain.append(str(x[0])+'.'+str(x[1])+'.*.*')
except IndexError:
cleandomain.append(str(x))
#if its in the CDN list, take a subdomain as well
elif len(x) > 3 and str(x[len(x)-2]).rstrip() in cdns:
try:
cleandomain.append(str(x[len(x)-3])+'.'+str(x[len(x)-2])+'.'+str(x[len(x)-1]))
except IndexError:
cleandomain.append(str(x))
elif len(x) > 3 and str(x[len(x)-3]).rstrip() in cdns:
try:
cleandomain.append(str(x[len(x)-4])+'.'+str(x[len(x)-3])+'.'+str(x[len(x)-2])+'.'+ str(x[len(x)-1]))
except IndexError:
cleandomain.append(str(x))
#if its in the TLD list, do this
elif len(x) > 2 and str(x[len(x)-2]).rstrip()+'.'+ str(x[len(x)-1]).rstrip() in tld:
try:
cleandomain.append(str(x[len(x)-3])+'.'+str(x[len(x)-2])+'.'+ str(x[len(x)-1]))
except IndexError:
cleandomain.append(str(x))
elif len(x) > 2 and str(x[len(x)-1]) in tld:
try:
cleandomain.append(str(x[len(x)-2])+'.'+ str(x[len(x)-1]))
except IndexError:
cleandomain.append(str(x))
#if its not in the TLD list, do this
else:
cleandomain.append(str(x))
#add the column to the dataframe
df3['newdomain2']=cleandomain
se = pd.Series(cleandomain)
df3['newdomain2'] = se.values
#select only the new domain column & usage
df4 = df3[['newdomain2', 'web.optimisedsize']]
#group by
df5 = df4.groupby(['newdomain2'])[['web.optimisedsize']].sum()
#sort
df6 = df5.sort_values(['web.optimisedsize'], ascending=["true"])
end = time.time()
print(df6)
print(end-start)
在路上，我有这个DF
In [4]: df
Out[4]:
Domain Use
0 graph.facebook.com 4242
1 news.bbc.co.uk 23423
2 news.more.news.bbc.co.uk 234432
3 profile.username.co 235523
4 offers.o2.co.uk 235523
5 subdomain.pyspark.org 2325
6 uds.data.domain.net 23523
7 domain.akamai.net 23532
8 333.333.333.333 3432324
在此期间，索引将其拆分为以下内容：
[['graph', 'facebook', 'com'], ['news', 'bbc' .....
然后，我将新域作为新列附加到原始数据帧中。然后将其按+进行分组，以创建最终数据框。
In [10]: df
Out[10]:
Domain Use newdomain
0 graph.facebook.com 4242 facebook.com
1 news.bbc.co.uk 23423 bbc.co.uk
2 news.more.news.bbc.co.uk 234432 bbc.co.uk
3 profile.username.co 235523 username.co
答案 0 :(得分：1)
问题之一是，在每次执行的迭代中，您都有index = df3.domain.str.split('.').tolist()。当我将此行放在循环之外时，计算速度快了2倍。 587毫秒VS 1.1秒。
我也认为您的代码是错误的。您无需使用row变量，而应使用index。而且，当您迭代索引时，一个元素始终是一个列表。因此if not isinstance(x, str)始终为True。 （您可以在下面的line_debugger输出中看到它）
字符串操作通常不可向量化。甚至.str表示法实际上都是python循环。
这是Jupyter笔记本中line_debugger工具的输出： 初始化（f是包裹在代码中的函数）：
%load_ext line_profiler
%lprun -f f f(df2, df3)
输出：
Total time: 1.82219 s
File: <ipython-input-8-79f01a353d31>
Function: f at line 1
Line # Hits Time Per Hit % Time Line Contents
==============================================================
1 def f(df2,df3):
2 1 8093.0 8093.0 0.2 index = df3.Domain.str.split('.').tolist()
3 #iterate through each row of the datafrme and split each domain at the dot
4 901 11775.0 13.1 0.2 for row in df2.itertuples():
5
6 900 26241.0 29.2 0.5 cleandomain = []
7 #iterate through each of the split domains
8 810900 971082.0 1.2 18.8 for x in index:
9 #if it isn't a string, then print the value directly in the cleandomain list
10 810000 1331253.0 1.6 25.8 if not isinstance(x, str):
11 810000 2819163.0 3.5 54.6 cleandomain.append(str(x))
12 #if it's a string that encapsulates numbers, then it's an IP
13 elif str(x)[-1].isnumeric():
14 try:
15 cleandomain.append(str(x[0])+'.'+str(x[1])+'.*.*')
16 except IndexError:
17 cleandomain.append(str(x))
18 #if its in the CDN list, take a subdomain as well
19 elif len(x) > 3 and str(x[len(x)-2]).rstrip() in cdns:
20 try:
21 cleandomain.append(str(x[len(x)-3])+'.'+str(x[len(x)-2])+'.'+str(x[len(x)-1]))
22 except IndexError:
23 cleandomain.append(str(x))
24 elif len(x) > 3 and str(x[len(x)-3]).rstrip() in cdns:
25 try:
26 cleandomain.append(str(x[len(x)-4])+'.'+str(x[len(x)-3])+'.'+str(x[len(x)-2])+'.'+ str(x[len(x)-1]))
27 except IndexError:
28 cleandomain.append(str(x))
29 #if its in the TLD list, do this
30 elif len(x) > 2 and str(x[len(x)-2]).rstrip()+'.'+ str(x[len(x)-1]).rstrip() in tld:
31 try:
32 cleandomain.append(str(x[len(x)-3])+'.'+str(x[len(x)-2])+'.'+ str(x[len(x)-1]))
33 except IndexError:
34 cleandomain.append(str(x))
35 elif len(x) > 2 and str(x[len(x)-1]) in tld:
36 try:
37 cleandomain.append(str(x[len(x)-2])+'.'+ str(x[len(x)-1]))
38 except IndexError:
39 cleandomain.append(str(x))
40 #if its not in the TLD list, do this
41 else:
42 cleandomain.append(str(x))
我的代码：
数据准备：
from io import StringIO
import pandas as pd
#import file into dataframe
TESTDATA=StringIO("""Domain,Use
graph.facebook.com, 4242
news.bbc.co.uk, 23423
news.more.news.bbc.co.uk, 234432
profile.username.co, 235523
offers.o2.co.uk, 235523
subdomain.pyspark.org, 2325
uds.data.domain.net, 23523
domain.akamai.net, 23532
333.333.333.333,3432324
""")
df=pd.read_csv(TESTDATA)
df["Domain"] = df.Domain.str.strip()
df = pd.concat([df]*100)
df2 = df
#extract only 2 columns from dataframe
df3 = df2
#define tld and cdn lookup lists
tld = ['co.uk', 'com', 'org', 'gov.uk', 'co', 'net', 'news', 'it', 'in' 'es', 'tw', 'pe', 'io', 'ca', 'cat', 'com.au',
'com.ar', 'com.mt', 'com.co', 'ws', 'to', 'es', 'de', 'us', 'br', 'im', 'gr', 'cc', 'cn', 'org.uk', 'me', 'ovh', 'be',
'tv', 'tech', '..', 'life', 'com.mx', 'pl', 'uk', 'ru', 'cz', 'st', 'info', 'mobi', 'today', 'eu', 'fi', 'jp', 'life',
'1', '2', '3', '4', '5', '6', '7', '8', '9', '0', 'earth', 'ninja', 'ie', 'im', 'ai', 'at', 'ch', 'ly', 'market', 'click',
'fr', 'nl', 'se']
cdns = ['akamai', 'maxcdn', 'cloudflare']
在jupyter笔记本中计时：
%%timeit
index = df3.Domain.str.split('.').tolist()
#iterate through each row of the datafrme and split each domain at the dot
for row in df2.itertuples():
cleandomain = []
#iterate through each of the split domains
for x in index:
#if it isn't a string, then print the value directly in the cleandomain list
if not isinstance(x, str):
cleandomain.append(str(x))
#if it's a string that encapsulates numbers, then it's an IP
elif str(x)[-1].isnumeric():
try:
cleandomain.append(str(x[0])+'.'+str(x[1])+'.*.*')
except IndexError:
cleandomain.append(str(x))
#if its in the CDN list, take a subdomain as well
elif len(x) > 3 and str(x[len(x)-2]).rstrip() in cdns:
try:
cleandomain.append(str(x[len(x)-3])+'.'+str(x[len(x)-2])+'.'+str(x[len(x)-1]))
except IndexError:
cleandomain.append(str(x))
elif len(x) > 3 and str(x[len(x)-3]).rstrip() in cdns:
try:
cleandomain.append(str(x[len(x)-4])+'.'+str(x[len(x)-3])+'.'+str(x[len(x)-2])+'.'+ str(x[len(x)-1]))
except IndexError:
cleandomain.append(str(x))
#if its in the TLD list, do this
elif len(x) > 2 and str(x[len(x)-2]).rstrip()+'.'+ str(x[len(x)-1]).rstrip() in tld:
try:
cleandomain.append(str(x[len(x)-3])+'.'+str(x[len(x)-2])+'.'+ str(x[len(x)-1]))
except IndexError:
cleandomain.append(str(x))
elif len(x) > 2 and str(x[len(x)-1]) in tld:
try:
cleandomain.append(str(x[len(x)-2])+'.'+ str(x[len(x)-1]))
except IndexError:
cleandomain.append(str(x))
#if its not in the TLD list, do this
else:
cleandomain.append(str(x))