我的目标是在可汗学院上尽可能多地抓取个人资料链接。然后在每个配置文件上抓取一些特定数据，将它们写入 CSV 文件。
我的问题很简单:脚本太慢了。
这是脚本:
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import TimeoutException,StaleElementReferenceException,NoSuchElementException
from bs4 import BeautifulSoup
import re
from requests_html import HTMLSession
session = HTMLSession()
r = session.get('https://www.khanacademy.org/computing/computer-programming/programming#intro-to-programming')
r.html.render(sleep=5)
soup=BeautifulSoup(r.html.html,'html.parser')
# first step: find all courses links and put them in a list
courses_links = soup.find_all(class_='link_1uvuyao-o_O-nodeStyle_cu2reh-o_O-nodeStyleIcon_4udnki')
list_courses={}
for links in courses_links:
courses = links.extract()
link_course = courses['href']
title_course= links.find(class_='nodeTitle_145jbuf')
span_title_course=title_course.span
text_span=span_title_course.text.strip()
final_link_course ='https://www.khanacademy.org'+link_course
list_courses[text_span]=final_link_course
# second step: loop the script down below with each course link in our list
for courses_step in list_courses.values():
# part 1: make selenium infinite click "schow more" button so we can then scrape as much profile links as possible
driver = webdriver.Chrome()
driver.get(courses_step)
while True: # might want to change that to do some testing
try:
showmore=WebDriverWait(driver, 15).until(EC.presence_of_element_located((By.CLASS_NAME,'button_1eqj1ga-o_O-shared_1t8r4tr-o_O-default_9fm203')))
showmore.click()
except TimeoutException:
break
except StaleElementReferenceException:
break
# part2: once the page fully loaded scrape all profile links and put them in a list
soup=BeautifulSoup(driver.page_source,'html.parser')
#find the profile links
driver.quit()
profiles = soup.find_all(href=re.compile("/profile/kaid"))
profile_list=[]
for links in profiles:
links_no_list = links.extract()
text_link = links_no_list['href']
text_link_nodiscussion = text_link[:-10]
final_profile_link ='https://www.khanacademy.org'+text_link_nodiscussion
profile_list.append(final_profile_link)
#remove profile link duplicates
profile_list=list(set(profile_list))
#print number of profiles we got in the course link
print('in this link:')
print(courses_step)
print('we have this number of profiles:')
print(len(profile_list))
#create the csv file
filename = "khan_withprojectandvotes.csv"
f = open(filename, "w")
headers = "link, date_joined, points, videos, questions, votes, answers, flags, project_request, project_replies, comments, tips_thx, last_date, number_project, projet_votes, projets_spins, topq_votes, topa_votes, sum_badges, badge_lvl1, badge_lvl2, badge_lvl3, badge_lvl4, badge_lvl5, badge_challenge\n"
f.write(headers)
#part 3: for each profile link, scrape the specific data and store them into the csv
for link in profile_list:
#print each profile link we are about to scrape
print("Scraping ",link)
session = HTMLSession()
r = session.get(link)
r.html.render(sleep=5)
soup=BeautifulSoup(r.html.html,'html.parser')
badge_list=soup.find_all(class_='badge-category-count')
badgelist=[]
if len(badge_list) != 0:
for number in badge_list:
text_num=number.text.strip()
badgelist.append(text_num)
number_badges=sum(list(map(int, badgelist)))
number_badges=str(number_badges)
badge_challenge=str(badgelist[0])
badge_lvl5=str(badgelist[1])
badge_lvl4=str(badgelist[2])
badge_lvl3=str(badgelist[3])
badge_lvl2=str(badgelist[4])
badge_lvl1=str(badgelist[5])
else:
number_badges='NA'
badge_challenge='NA'
badge_lvl5='NA'
badge_lvl4='NA'
badge_lvl3='NA'
badge_lvl2='NA'
badge_lvl1='NA'
user_info_table=soup.find('table', class_='user-statistics-table')
if user_info_table is not None:
dates,points,videos=[tr.find_all('td')[1].text for tr in user_info_table.find_all('tr')]
else:
dates=points=videos='NA'
user_socio_table=soup.find_all('div', class_='discussion-stat')
data = {}
for gettext in user_socio_table:
category = gettext.find('span')
category_text = category.text.strip()
number = category.previousSibling.strip()
data[category_text] = number
full_data_keys=['questions','votes','answers','flags raised','project help requests','project help replies','comments','tips and thanks'] #might change answers to answer because when it's 1 it's putting NA instead
for header_value in full_data_keys:
if header_value not in data.keys():
data[header_value]='NA'
user_calendar = soup.find('div',class_='streak-calendar-scroll-container')
if user_calendar is not None:
last_activity = user_calendar.find('span',class_='streak-cell filled')
try:
last_activity_date = last_activity['title']
except TypeError:
last_activity_date='NA'
else:
last_activity_date='NA'
session = HTMLSession()
linkq=link+'discussion/questions'
r = session.get(linkq)
r.html.render(sleep=5)
soup=BeautifulSoup(r.html.html,'html.parser')
topq_votes=soup.find(class_='text_12zg6rl-o_O-LabelXSmall_mbug0d-o_O-votesSum_19las6u')
if topq_votes is not None:
topq_votes=topq_votes.text.strip()
topq_votes=re.findall('\d+', topq_votes)
topq_votes=topq_votes[0]
#print(topq_votes)
else:
topq_votes='0'
session = HTMLSession()
linka=link+'discussion/answers'
r = session.get(linka)
r.html.render(sleep=5)
soup=BeautifulSoup(r.html.html,'html.parser')
topa_votes=soup.find(class_='text_12zg6rl-o_O-LabelXSmall_mbug0d-o_O-votesSum_19las6u')
if topa_votes is not None:
topa_votes=topa_votes.text.strip()
topa_votes=re.findall('\d+', topa_votes)
topa_votes=topa_votes[0]
else:
topa_votes='0'
# infinite click on show more button for each profile link project section and then scrape data
with webdriver.Chrome() as driver:
wait = WebDriverWait(driver,10)
driver.get(link+'projects')
while True:
try:
showmore = wait.until(EC.presence_of_element_located((By.CSS_SELECTOR,'[class^="showMore"] > a')))
driver.execute_script("arguments[0].click();",showmore)
except Exception:
break
soup = BeautifulSoup(driver.page_source,'html.parser')
driver.quit()
project = soup.find_all(class_='title_1usue9n')
prjct_number = str(len(project))
votes_spins=soup.find_all(class_='stats_35behe')
list_votes=[]
for votes in votes_spins:
numbvotes=votes.text.strip()
numbvotes=re.split(r'\s',numbvotes)
list_votes.append(numbvotes[0])
prjct_votes=str(sum(list(map(int, list_votes))))
list_spins=[]
for spins in votes_spins:
numspins=spins.text.strip()
numspins=re.split(r'\s',numspins)
list_spins.append(numspins[3])
number_spins=list(map(int, list_spins))
number_spins = [0 if i < 0 else i for i in number_spins]
prjct_spins=str(sum(number_spins))
f.write(link + "," + dates + "," + points.replace("," , "") + "," + videos + "," + data['questions'] + "," + data['votes'] + "," + data['answers'] + "," + data['flags raised'] + "," + data['project help requests'] + "," + data['project help replies'] + "," + data['comments'] + "," + data['tips and thanks'] + "," + last_activity_date + "," + prjct_number + "," + prjct_votes + "," + prjct_spins + "," + topq_votes + "," + topa_votes + "," + number_badges + "," + badge_lvl1 + ',' + badge_lvl2 + ',' + badge_lvl3 + ',' + badge_lvl4 + ',' + badge_lvl5 + ',' + badge_challenge + ',' + "\n")
你有什么建议吗？ (一些代码可以帮助我理解)
所需的输出应如下所示(但行数更多):
最佳答案
该脚本花费大量时间的一个原因是它发送的请求数量众多，它消耗更少时间的一种方法是限制请求数量。这可以通过使用他们的内部 API 来获取配置文件数据来实现。例如:发送一个get请求到这个链接https://www.khanacademy.org/api/internal/user/discussion/summary?username=user_name&lang=en (并将 user_name 更改为实际用户名)将返回您需要(以及更多)的配置文件数据作为 JSON，而不必抓取许多来源。然后，您可以从 JSON 输出中提取数据，并将它们转换为 CSV。您将需要使用 selenium 仅获取讨论数据并查找用户名列表。这将大大缩短脚本运行时间。
旁注:即使是模块链接也可以使用抓取主 URL 时解析的 JS 变量来提取。该变量包含存储类(class)数据(包括链接)的 JSON。
这是执行此操作的代码:
import requests
import bs4
import json
URL = "https://www.khanacademy.org/computing/computer-programming/programming#intro-to-programming"
BASE_URL = "https://www.khanacademy.org"
response = requests.get(URL)
soup = bs4.BeautifulSoup(response.content, 'lxml')
script = soup.find_all('script')[18]
script = script.text.encode('utf-8')
script = unicode(script, errors='ignore').encode('utf-8').strip()
script = script.split('{window["./javascript/app-shell-package/app-entry.js"] = ')[1]
script = script[:-2]
json_content = json.loads(script)
您可以从该 JSON 中提取模块链接，并改为查询它们。
关于python-3.x - 有没有办法让 Selenium 异步工作？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55433083/