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core.py
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core.py
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#!/usr/bin/env python
import re
from time import sleep
from typing import Optional, Union, Generator, List, Any
from requests_html import HTMLSession
class Spider:
"""Base class for all web spiders.
Attributes:
name: The name of the spider.
start_urls: The list of URLs to start scraping from.
extra_urls: The URLs that added after the start URLs.
requests_delay: The delay between requests.
"""
name: Optional[str] = None
start_urls: Optional[List[str]] = []
extra_urls: Optional[List[str]] = []
requests_delay: Optional[Union[int, float]] = 0
def __init__(self) -> None:
self.name = self.name if self.name is not None else self.__class__.__name__
self.session = HTMLSession()
def __str__(self) -> str:
return f'{self.__class__.__name__}(name={repr(self.name)}, start_urls={self.start_urls}, extra_urls={self.extra_urls})'
def __repr__(self) -> str:
return str(self)
def __eq__(self, other: object) -> bool:
return self.start_urls == other.start_urls and self.extra_urls == other.extra_urls
def setup(self, *args, **kwargs) -> None:
"""Setups the spiders before starting."""
if kwargs.get('start_urls') is not None:
self.start_urls = kwargs.get('start_urls')
if kwargs.get('extra_urls') is not None:
self.extra_urls = kwargs.get('extra_urls')
def fetch(self) -> Generator[Any, None, None]:
"""Goes between all the specified URLs."""
print(f'{self.name} started...')
requests_count = 0
for url in self.start_urls:
requests_count += 1
print(f'\nFetching request #{requests_count} from {url}')
response = self.session.get(url)
for item in self.parse(response):
yield item
sleep(self.requests_delay)
for url in self.extra_urls:
requests_count += 1
print(f'\nFetching request #{requests_count} from {url}')
response = self.session.get(url)
for item in self.parse(response):
yield item
sleep(self.requests_delay)
print('Done!')
def parse(self, response: HTMLSession) -> Generator[Any, None, None]:
"""Parses the response and yields items."""
raise NotImplementedError
def _build_articles_query(**kwargs) -> str:
"""Builds the articles and case law query from the given arguments."""
keywords = f'q={kwargs.get("keywords").replace(" ", "+")}'
year_range = f'as_ylo={kwargs.get("start_year")}&as_yhi={kwargs.get("end_year")}'
languages = f'lr={"|".join([f"lang_{l}" for l in kwargs.get("languages", [])])}'
return f'hl=en&{keywords}&{year_range}&{languages}&{kwargs.get("extra", "")}'
class GSArticlesSpider(Spider):
"""Google Scholar articles category spider."""
name = 'Google Scholar articles spider'
requests_delay = .5
def setup(self, *args, **kwargs) -> None:
query = _build_articles_query(**kwargs, extra='as_sdt=0,5')
self.start_urls.append(f'https://scholar.google.com/scholar?{query}')
def parse(self, response: HTMLSession) -> Generator[dict, None, None]:
articles = response.html.xpath('//div[@class="gs_r gs_or gs_scl"]')
for article in articles:
title = article.xpath('//h3[@class="gs_rt"]/a | .//h3[@class="gs_rt"]/span[2]', first=True).text
snippet = article.xpath('//div[@class="gs_a"]', first=True).text
snippet = [elem.strip() for elem in snippet.replace('\xa0', '').split('- ')]
authors = snippet[0]
if year := None or len(snippet) >= 2:
year = re.search(r'\d{4,}$', snippet[-2]) or re.search(r'\d{4,}$', snippet[-1])
year = year.group() if year is not None else None
source = article.xpath('//h3[@class="gs_rt"]/a/@href', first=True)
paper = article.xpath('//div[@class="gs_or_ggsm"]/a/@href', first=True)
citations_no = article.xpath('//div[@class="gs_ri"]/div[contains(@class, "gs_fl")]/a[3][contains(., "Cited by")]', first=True)
citations_no = citations_no.text.replace('Cited by ', '') if citations_no is not None else None
yield {
'title': title,
'authors': authors,
'year': year,
'source': source,
'paper': paper,
'citations no.': citations_no,
}
next_page = response.html.xpath('//div[@id="gs_res_ccl_bot"]//td[@align="left"]/a/@href', first=True)
if next_page is not None:
next_page_url = f'https://scholar.google.com{next_page}'
print(f'Next page found at {next_page_url}')
self.extra_urls.append(next_page_url)
class GSCaseLawSpider(Spider):
"""Google Scholar case law category spider."""
name = 'Google Scholar case law spider'
requests_delay = .5
def setup(self, *args, **kwargs) -> None:
query = _build_articles_query(**kwargs, extra='as_sdt=2006')
self.start_urls.append(f'https://scholar.google.com/scholar?{query}')
def parse(self, response: HTMLSession) -> Generator[dict, None, None]:
articles = response.html.xpath('//div[@class="gs_r gs_or gs_scl"]')
for article in articles:
title = article.xpath('//h3[@class="gs_rt"]/a | .//h3[@class="gs_rt"]/span[2]', first=True).text
snippet = article.xpath('//div[@class="gs_a"]', first=True).text
snippet = [elem.strip() for elem in snippet.replace('\xa0', '').split('- ')]
if year := None or len(snippet) >= 2:
year = re.search(r'\d{4,}$', snippet[-2]) or re.search(r'\d{4,}$', snippet[-1])
year = year.group() if year is not None else None
case_ = ' - '.join(snippet[:2]) if len(snippet) > 1 else snippet[0]
case_ = re.split(r' ?[\-,] \d+$', case_)[0]
source = article.xpath('//h3[@class="gs_rt"]/a/@href', first=True)
source = f'https://scholar.google.com{source}' if source is not None else None
citations_no = article.xpath('//div[@class="gs_ri"]/div[contains(@class, "gs_fl")]/a[3][contains(., "Cited by")]', first=True)
citations_no = citations_no.text.replace('Cited by ', '') if citations_no is not None else None
yield {
'title': title,
'case': case_,
'year': year,
'source': source,
'citations no.': citations_no,
}
next_page = response.html.xpath('//div[@id="gs_res_ccl_bot"]//td[@align="left"]/a/@href', first=True)
if next_page is not None:
next_page_url = f'https://scholar.google.com{next_page}'
print(f'Next page found at {next_page_url}')
self.extra_urls.append(next_page_url)
class GSProfilesSpider(Spider):
"""Google Scholar profiles category spider."""
name = 'Google Scholar profiles spider'
requests_delay = .5
def setup(self, *args, **kwargs) -> None:
query = f'hl=en&user={kwargs.get("keywords")}&cstart=0&pagesize=100'
self.start_urls.append(f'https://scholar.google.com/citations?{query}')
self.cstart = 0
def parse(self, response: HTMLSession) -> Generator[dict, None, None]:
articles = response.html.xpath('//tr[@class="gsc_a_tr"]')
for article in articles:
title = article.xpath('//a[@class="gsc_a_at"]', first=True).text
authors = article.xpath('//div[@class="gs_gray"][1]', first=True).text
source = article.xpath('//a[@class="gsc_a_at"]/@href', first=True)
source = f'https://scholar.google.com{source}' if source is not None else None
year = article.xpath('//span[@class="gsc_a_h gsc_a_hc gs_ibl"]/text()', first=True)
citations_no = article.xpath('//a[@class="gsc_a_ac gs_ibl"]', first=True)
citations_no = int(citations_no.text) if citations_no is not None and citations_no.text else None
yield {
'title': title,
'authors': authors,
'source': source,
'year': year,
'citations no.': citations_no,
}
next_page = response.html.xpath('//button[@class="gs_btnPD gs_in_ib gs_btn_flat gs_btn_lrge gs_btn_lsu"]', first=True)
if next_page.attrs.get('disabled') is None:
current_page_url = response.url
next_page_url = current_page_url.replace(f'cstart={self.cstart}', f'cstart={self.cstart+100}')
self.cstart += 100
print(f'Next articles found at {next_page_url}')
self.extra_urls.append(next_page_url)
if __name__ == '__main__':
import os
import sys
import argparse
from pathlib import Path
import pandas as pd
parser = argparse.ArgumentParser(description='Scrapes Google Scholar for articles, case law, and profiles.')
parser.add_argument('keywords', type=str, help='the keywords to search for')
parser.add_argument('-c', '--case-law', action='store_true', help='search for case law')
parser.add_argument('-p', '--profiles', action='store_true', help='search for a profile articles')
parser.add_argument('-s', '--start-year', type=int, help='the start year')
parser.add_argument('-e', '--end-year', type=int, help='the end year')
parser.add_argument('-l', '--languages', nargs='+', default=['en'], help='allowed languages (default: en)')
parser.add_argument('-o', '--output', type=str, default='output.csv', help='the output file (default: output.csv)')
parser.add_argument('-y', '--year', action='store_true', help='sort by year')
parser.add_argument('-q', '--quiet', action='store_true', help='do not print progress')
args = parser.parse_args()
if args.quiet:
sys.stdout = open(os.devnull, 'w')
params = {
'keywords': args.keywords,
'start_year': args.start_year,
'end_year': args.end_year,
'languages': args.languages,
}
if args.case_law:
gs_spider = GSCaseLawSpider()
elif args.profiles:
gs_spider = GSProfilesSpider()
else:
gs_spider = GSArticlesSpider()
gs_spider.setup(**params)
results = pd.DataFrame(gs_spider.fetch())
if results.empty:
print('No results found. Try again later or change your IP address.')
sys.exit(1)
if args.year:
results.sort_values('year', ascending=False, inplace=True)
else:
results.sort_values('citations no.', ascending=False, inplace=True)
Path(args.output).parent.mkdir(parents=True, exist_ok=True)
if args.output.endswith('.csv'):
results.to_csv(args.output, index=False)
elif args.output.endswith('.json'):
results.to_json(args.output, indent=4)
elif args.output.endswith('.html'):
results.to_html(args.output)
else:
print('The format is not supported, but I will print the results on the screen...')
print(results.to_string())