Python：如何使用关键字列表在文本中搜索字符串

Question

所以我正在编写一个循环多个 .txt 文件并搜索任意数量的预先指定关键字的程序。我很难找到一种方法来通过要搜索的关键字列表。

下面的代码目前返回如下错误：

TypeError: 'in <string>' requires string as left operand, not list

我知道错误是由关键字列表引起的，但我不知道如何输入大量关键字而不出现此错误。

当前代码：

from os import listdir

keywords=['Example', 'Use', 'Of', 'Keywords']
 
with open("/home/user/folder/project/result.txt", "w") as f:
    for filename in listdir("/home/user/folder/project/data"):
        with open('/home/user/folder/project/data/' + filename) as currentFile:
            text = currentFile.read()
            #Error Below
            if (keywords in text):
                f.write('Keyword found in ' + filename[:-4] + '\n')
            else:
                f.write('No keyword in ' + filename[:-4] + '\n')

上述代码的第 10 行在注释部分下指出了错误。我不确定为什么我不能调用列表来搜索关键字。任何帮助表示赞赏，谢谢！

Answer 1

你可以替换

if (keywords in text):
   ...

与

if any(keyword in text for keyword in keywords):
   ...

Answer 2

尝试循环遍历列表以查看每个元素是否在文本中

for i in range(0, len(keywords)):
    if keywords[i] in text:
        f.write('Keyword found in ' + filename[:-4] + '\n')
        break
    else:
        f.write('No keyword in ' + filename[:-4] + '\n')
        break

您也不能使用in 来查看列表是否在字符串中

Answer 3

我会使用regular expressions，因为它们是专门为在文本中搜索子字符串而构建的。

您只需要 re.search 块。我添加了findall 和finditer 的示例来揭开它们的神秘面纱。

# lets pretend these 4 sentences in `text` are 4 different files
text = '''Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum'''.split(sep='. ')

# add more keywords
keywords=[r'publishing', r'industry']
regex = '|'.join(keywords)
import re
for t in text:
    lst = re.findall(regex, t, re.I) # re.I make case-insensitive
    for el in lst:
        print(el)

    iterator = re.finditer(regex, t, re.I)
    for el in iterator:
        print(el.span())

    if re.search(regex, t, re.I):
        print('Keyword found in `' + t + '`\n')
    else:
        print('No keyword in `' + t + '`\n')

输出：

industry
(65, 73)
Keyword found in `Lorem Ipsum is simply dummy text of the printing and typesetting industry`

industry
(25, 33)
Keyword found in `Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book`

No keyword in `It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged`

publishing
(132, 142)
Keyword found in `It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum`