python - 使用 Regex 和 BeautifulSoup 解析 Python 中的字符串

Question

我有一系列类似于“Saturday, December 27th 2014”的字符串，我想丢弃“Saturday”并使用名称“141227”(年+月+日)保存文件。到目前为止，一切正常，除了我无法让 daypos 或 Yearpos 的正则表达式工作。他们都给出了相同的错误:

Traceback (most recent call last): File "scrapewaybackblog.py", line 17, in daypos = byline.find(re.compile("[A-Z][a-z]*\s")) TypeError: expected a character buffer object

什么是字符缓冲区对象？这是不是说明我的表情有问题？这是我的脚本:

for i in xrange(3, 1, -1):
       page = urllib2.urlopen("http://web.archive.org/web/20090204221349/http://www.americansforprosperity.org/nationalblog?page={}".format(i))
       soup = BeautifulSoup(page.read())
       snippet = soup.find_all('div', attrs={'class': 'blog-box'})
       for div in snippet:
           byline =  div.find('div', attrs={'class': 'date'}).text.encode('utf-8')
           text = div.find('div', attrs={'class': 'right-box'}).text.encode('utf-8')

           monthpos = byline.find(",")
           daypos = byline.find(re.compile("[A-Z][a-z]*\s"))
           yearpos = byline.find(re.compile("[A-Z][a-z]*\D\d*\w*\s"))
           endpos = monthpos + len(byline)

           month = byline[monthpos+1:daypos]
           day = byline[daypos+0:yearpos]
           year = byline[yearpos+2:endpos]

           output_files_pathname = 'Data/'  # path where output will go
           new_filename = year + month + day + ".txt"
           outfile = open(output_files_pathname + new_filename,'w')
           outfile.write(date)
           outfile.write("\n")
           outfile.write(text)
           outfile.close()
       print "finished another url from page {}".format(i)

我还没有弄清楚如何使 12 月 = 12，但那是另一次了。请帮我找到合适的职位。

Answer 1

不要用正则表达式解析日期字符串，而是用 dateutil 解析它。 :

from dateutil.parser import parse

for div in soup.select('div.blog-box'):
    byline = div.find('div', attrs={'class': 'date'}).text.encode('utf-8')
    text = div.find('div', attrs={'class': 'right-box'}).text.encode('utf-8')

    dt = parse(byline)
    new_filename = "{dt.year}{dt.month}{dt.day}.txt".format(dt=dt)
    ...

或者，您可以使用datetime.strptime()解析字符串，但您需要注意 suffixes :

byline = re.sub(r"(?<=\d)(st|nd|rd|th)", "", byline)
dt = datetime.strptime(byline, '%A, %B %d %Y')

re.sub() 此处查找 st 或 nd 或 rd 或 th字符串after a digit并将后缀替换为空字符串。之后的日期字符串将匹配 '%A, %B %d %Y' 格式，请参阅:

• strftime() and strptime() Behavior

---

一些附加说明:

• 您可以将 urlopen() 的结果直接传递给 BeautifulSoup 构造函数
• 使用 CSS Selector 而不是按类名 find_all() div.blog-box
• 要加入系统路径，请使用 os.path.join()
• 使用with context manager处理文件时

修复版本:

import os
import urllib2

from bs4 import BeautifulSoup
from dateutil.parser import parse


for i in xrange(3, 1, -1):
    page = urllib2.urlopen("http://web.archive.org/web/20090204221349/http://www.americansforprosperity.org/nationalblog?page={}".format(i))
    soup = BeautifulSoup(page)

    for div in soup.select('div.blog-box'):
        byline = div.find('div', attrs={'class': 'date'}).text.encode('utf-8')
        text = div.find('div', attrs={'class': 'right-box'}).text.encode('utf-8')

        dt = parse(byline)

        new_filename = "{dt.year}{dt.month}{dt.day}.txt".format(dt=dt)
        with open(os.path.join('Data', new_filename), 'w') as outfile:
            outfile.write(byline)
            outfile.write("\n")
            outfile.write(text)

    print "finished another url from page {}".format(i)