python - Pandas:将所有 re.search 结果从 BeautifulSoup 写入 csv

Question

我有一个 Python pandas 脚本的开头，它在 Google 上搜索值并获取它可以在第一页上找到的任何 PDF 链接。

我有两个问题，如下所示。

import pandas as pd
from bs4 import BeautifulSoup
import urllib2
import re

df = pd.DataFrame(["Shakespeare", "Beowulf"], columns=["Search"])    

print "Searching for PDFs ..."

hdr = {"User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11",
    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
    "Accept-Charset": "ISO-8859-1,utf-8;q=0.7,*;q=0.3",
    "Accept-Encoding": "none",
    "Accept-Language": "en-US,en;q=0.8",
    "Connection": "keep-alive"}

def crawl(search):
    google = "http://www.google.com/search?q="
    url = google + search + "+" + "PDF"
    req = urllib2.Request(url, headers=hdr)

    pdf_links = None
    placeholder = None #just a column placeholder

    try:
        page = urllib2.urlopen(req).read()
        soup = BeautifulSoup(page)
        cite = soup.find_all("cite", attrs={"class":"_Rm"})
        for link in cite:
            all_links = re.search(r".+", link.text).group().encode("utf-8")
            if all_links.endswith(".pdf"):
                pdf_links = re.search(r"(.+)pdf$", all_links).group()
            print pdf_links

    except urllib2.HTTPError, e:
        print e.fp.read()

    return pd.Series([pdf_links, placeholder])

df[["PDF links", "Placeholder"]] = df["Search"].apply(crawl)

df.to_csv(FileName, index=False, delimiter=",")

---

print pdf_links 的结果将是:

davidlucking.com/documents/Shakespeare-Complete%20Works.pdf
sparks.eserver.org/books/shakespeare-tempest.pdf
www.w3.org/People/maxf/.../hamlet.pdf
www.w3.org/People/maxf/.../hamlet.pdf
www.w3.org/People/maxf/.../hamlet.pdf
www.w3.org/People/maxf/.../hamlet.pdf
www.w3.org/People/maxf/.../hamlet.pdf
www.w3.org/People/maxf/.../hamlet.pdf
www.w3.org/People/maxf/.../hamlet.pdf
calhoun.k12.il.us/teachers/wdeffenbaugh/.../Shakespeare%20Sonnets.pdf
www.yorku.ca/inpar/Beowulf_Child.pdf
www.yorku.ca/inpar/Beowulf_Child.pdf
https://is.muni.cz/el/1441/.../2._Beowulf.pdf
https://is.muni.cz/el/1441/.../2._Beowulf.pdf
https://is.muni.cz/el/1441/.../2._Beowulf.pdf
https://is.muni.cz/el/1441/.../2._Beowulf.pdf
www.penguin.com/static/pdf/.../beowulf.pdf
www.neshaminy.org/cms/lib6/.../380/text.pdf
www.neshaminy.org/cms/lib6/.../380/text.pdf
sparks.eserver.org/books/beowulf.pdf

csv 输出将如下所示:

Search         PDF Links
Shakespeare    calhoun.k12.il.us/teachers/wdeffenbaugh/.../Shakespeare%20Sonnets.pdf
Beowulf        sparks.eserver.org/books/beowulf.pdf

---

问题:

• 有没有办法将所有结果作为行写入 csv 而不是 只是最下面那一个吗？如果可能，请在 Search 中包含与 “Shakespeare” 或 “Beowulf” 对应的每一行的值？
• 如何写出完整的 pdf 链接，而不让长链接自动缩写为 "..."？

Answer 1

这将使用 soup.find_all("a",href=True) 为您提供所有正确的 pdf 链接，并将它们保存在 Dataframe 和 csv 中:

hdr = {
    "User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11",
    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
    "Accept-Charset": "ISO-8859-1,utf-8;q=0.7,*;q=0.3",
    "Accept-Encoding": "none",
    "Accept-Language": "en-US,en;q=0.8",
    "Connection": "keep-alive"}


def crawl(columns=None, *search):
    df = pd.DataFrame(columns= columns)
    for term in search:
        google = "http://www.google.com/search?q="
        url = google + term + "+" + "PDF"
        req = urllib2.Request(url, headers=hdr)
        try:
            page = urllib2.urlopen(req).read()
            soup = BeautifulSoup(page)
            pdfs = []
            links = soup.find_all("a",href=True)
            for link in links:
                lk = link["href"]
                if lk.endswith(".pdf"):
                     pdfs.append((term, lk))
            df2 = pd.DataFrame(pdfs, columns=columns)
            df = df.append(df2, ignore_index=True)
        except urllib2.HTTPError, e:
            print e.fp.read()
    return df


df = crawl(["Search", "PDF link"],"Shakespeare","Beowulf")
df.to_csv("out.csv",index=False)

输出.csv:

Search,PDF link
Shakespeare,http://davidlucking.com/documents/Shakespeare-Complete%20Works.pdf
Shakespeare,http://www.w3.org/People/maxf/XSLideMaker/hamlet.pdf
Shakespeare,http://sparks.eserver.org/books/shakespeare-tempest.pdf
Shakespeare,https://phillipkay.files.wordpress.com/2011/07/william-shakespeare-plays.pdf
Shakespeare,http://www.artsvivants.ca/pdf/eth/activities/shakespeare_overview.pdf
Shakespeare,http://triggs.djvu.org/djvu-editions.com/SHAKESPEARE/SONNETS/Download.pdf
Beowulf,http://www.yorku.ca/inpar/Beowulf_Child.pdf
Beowulf,https://is.muni.cz/el/1441/podzim2013/AJ2RC_STAL/2._Beowulf.pdf
Beowulf,http://teacherweb.com/IL/Steinmetz/MottramM/Beowulf---Seamus-Heaney.pdf
Beowulf,http://www.penguin.com/static/pdf/teachersguides/beowulf.pdf
Beowulf,http://www.neshaminy.org/cms/lib6/PA01000466/Centricity/Domain/380/text.pdf
Beowulf,http://www.sparknotes.com/free-pdfs/uscellular/download/beowulf.pdf