python - 如何修改文件以替换与此模式匹配的字符串

Question

我有一个像这样的 json 文件:

{
    "title": "Pilot",
    "image": [
        {
            "resource": "http://images2.nokk.nocookie.net/__cb20110227141960/notr/images/8/8b/pilot.jpg",
            "description": "not yet implemented"
        }
    ],
    "content": "<p>The pilot ...</p>"
},
{
    "title": "Special Christmas (Part 1)",
    "image": [
        {
            "resource": "http://images1.nat.nocookie.net/__cb20090519172121/obli/images/e/ed/SpecialChristmas.jpg",
            "description": "not yet implemented"
        }
    ],
    "content": "<p>Last comment...</p>"
}

我需要替换文件中所有资源值的内容，所以如果 字符串具有以下格式:

"http://images1.nat.nocookie.net/__cb20090519172121/obli/images/e/ed/SpecialChristmas.jpg"

结果应该是:

"../img/SpecialChristmas.jpg"

有人可以告诉我如何匹配该模式以修改文件吗？

我尝试过类似的建议:

https://stackoverflow.com/a/4128192/521728

但我不知道如何使其适应我的情况。

提前致谢!

Answer 1

我将正则表达式与组一起使用:

from StringIO import StringIO    
import re

reader = StringIO("""{
    "title": "Pilot",
    "image": [
        {
            "resource": "http://images2.nokk.nocookie.net/__cb20110227141960/notr/images/8/8b/pilot.jpg",
            "description": "not yet implemented"
        }
    ],
    "content": "<p>The pilot ...</p>"
},
{
    "title": "Special Christmas (Part 1)",
    "image": [
        {
            "resource": "http://images1.nat.nocookie.net/__cb20090519172121/obli/images/e/ed/SpecialChristmas.jpg",
            "description": "not yet implemented"
        }
    ],
    "content": "<p>Last comment...</p>"
}""")

# to open a file just use reader = open(filename)

text = reader.read()
pattern = r'"resource": ".+/(.+).jpg"'
replacement = '"resource": "../img/\g<1>.jpg"'
text = re.sub(pattern, replacement, text)

print(text)

解释该模式。 "resource": ".+/(.+)?.jpg" :查找以 "resource": " 开头的任何文本然后在正斜杠之前有一个或多个字符然后在 .jpg" 之前有一个或多个字符。括号()意思是我想要作为一个团体在里面找到什么。由于我只有一组括号，我可以在替换中使用 '\g<1>' 访问它。 (请注意 '\g<0>' 将匹配整个字符串:' "resources": etc'`)