如何使用glob读取具有数字名称的有限文件集? [英] How to use glob to read limited set of files with numeric names?

问题描述

如何使用glob仅读取有限的文件集?

How to use glob to only read limited set of files?

我在同一目录中有json文件，它们的编号从50到20000(例如50.json，51.json，52.json ... 19999.json，20000.json).我只想读取编号从15000到18000的文件.

I have json files named numbers from 50 to 20000 (e.g. 50.json,51.json,52.json...19999.json,20000.json) within the same directory. I want to read only the files numbered from 15000 to 18000.

为此，我使用了一个glob，如下所示，但是每次我尝试过滤出数字时，它都会生成一个空列表.我已尽力遵循此链接( https://docs.python.org/2/library/glob.html )，但我不确定自己做错了什么.

To do so I'm using a glob, as shown below, but it generates an empty list every time I try to filter out for the numbers. I've tried my best to follow this link (https://docs.python.org/2/library/glob.html), but I'm not sure what I'm doing wrong.

>>> directory = "/Users/Chris/Dropbox"
>>> read_files = glob.glob(directory+"/[15000-18000].*")
>>> print read_files
[]

另外，如果我想要大于18000的文件怎么办?

Also, what if I wanted files with any number greater than 18000?

推荐答案

您错误地使用了glob语法； [..]序列对每个字符有效 .以下glob将改为正确匹配您的文件:

You are using the glob syntax incorrectly; the [..] sequence works per character. The following glob would match your files correctly instead:

'1[5-8][0-9][0-9][0-9].*'

在幕后，glob使用fnmatch将模式转换为正则表达式.您的模式将转换为:

Under the covers, glob uses fnmatch which translates the pattern to a regular expression. Your pattern translates to:

>>> import fnmatch
>>> fnmatch.translate('[15000-18000].*')
'[15000-18000]\\..*\\Z(?ms)'

与.，0，1，5或8前面的 1 字符匹配的

.没什么.

which matches 1 character before the ., a 0, 1, 5 or 8. Nothing else.

glob模式非常有限；匹配数字范围并不容易；您必须为范围(例如glob('1[8-9][0-9][0-9][0-9]') + glob('2[0-9][0-9][0-9][0-9]')等)创建单独的全局文件.

glob patterns are quite limited; matching numeric ranges is not easy with it; you'd have to create separate globs for ranges, for example (glob('1[8-9][0-9][0-9][0-9]') + glob('2[0-9][0-9][0-9][0-9]'), etc.).

请自行过滤:

directory = "/Users/Chris/Dropbox"

for filename in os.listdir(directory):
    basename, ext = os.path.splitext(filename)
    if ext != '.json':
        continue
    try:
        number = int(basename)
    except ValueError:
        continue  # not numeric
    if 18000 <= number <= 19000:
        # process file
        filename = os.path.join(directory, filename)

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