Question

第一次发帖和一点菜鸟所以如果礼仪或格式有任何问题，请告诉我。

我正在尝试使用文件上的grep函数（下图）来检查文件中是否存在单词。当我查看文件时，这个词肯定存在。它被空格包围，是一行中的最后一个字。

由于某种原因，grep无法找到该单词且程序返回0.为什么？

谢谢！

import os
import re

word = "aliows"
folder = '/Users/jordanfreedman/Thinkful/Projects/Spam_Filter/enron1/spam/'
email = '4201.2005-04-05.GP.spam.txt'

number = int(os.popen("grep -w -i -l " + word + " " + folder + email + " | wc -l").read())
print number

Answer 1

您可以使用退出状态找出是否匹配：

import os
from subprocess import STDOUT, call

path = os.path.join(folder, email)
with open(os.devnull, 'wb', 0) as devnull:
   rc = call(['grep', '-w', '-l', '-i', '-F', word, path],
             stdout=devnull, stderr=STDOUT)
if rc == 0: 
    print('found')
elif rc == 1:
    print('not found')
else:
    print('error')

或as @stevieb mentioned，您可以在纯Python中找到该单词是否在给定文件中：

import re
from contextlib import closing
from mmap import ACCESS_READ, mmap

with open(path) as f, closing(mmap(f.fileno(), 0, access=ACCESS_READ)) as m:
   if re.search(br"(?i)\b%s\b" % re.escape(word), m):
       print('found')

Answer 2

您需要发布文件片段，以便我们测试grep语句。此外，没有理由拒绝：

import re

word = "aliows"
folder = '/Users/jordanfreedman/Thinkful/Projects/Spam_Filter/enron1/spam/'
email = '4201.2005-04-05.GP.spam.txt'

file = folder + email
fh = open(file, 'r')

contents = re.findall(word, fh.read())

print(len(contents))

为什么grep在文件中肯定没找到字符串？

2 个答案: