python - 使用循环将文件名与列表匹配，忽略已经 "processed"文件

Question

我想要做的是匹配一组文件并整理出我想要的文件(匹配扩展名)，忽略我已经使用列表处理过的其他文件

到目前为止我想到的是

mylist = []
extensions = ['*.txt', '*.foo', '*.bar']
for dirpath, dirnames, filenames in os.walk(directory):
    skip = None
    for ext in extensions:
        for filename in fnmatch.filter(filenames, ext):
            for test in mylist:
                if test == filename:
                    skip = True
            if not skip:
                ## do my thing
                mylist.append(filename)

但它忽略了我的 if 测试语句。我会瞎吗？

Answer 1

您正在设置 skip = True 但从未重置 skip，因此一旦您跳过了一个文件名，其余的也会被跳过。此外，一个简单的 if filename not in mylist 就足够了，不需要执行显式循环。

但是，您希望在此处使用 set 进行快速成员资格测试，并且在任何情况下都可以简化逻辑:

seen = set()
extensions = ['*.txt', '*.foo', '*.bar']
for dirpath, dirnames, filenames in os.walk(directory):
    for ext in extensions:
        for filename in fnmatch.filter(filenames, ext):
            if filename not in seen:
                # do your thing
                seen.add(filename)

接下来，我们可以去掉这里的 fnmatch.filter 选项，使用 .endswith() 会更简单、更快:

seen = set()
extensions = ('.txt', '.foo', '.bar')
for dirpath, dirnames, filenames in os.walk(directory):
    for filename in filenames:
        if filename.endswith(extensions) and filename not in seen:
            # do your thing
            seen.add(filename)

.endswith() 可以查找一个元组字符串；在本例中是您的扩展序列。

如果您只想考虑不带扩展名的文件名，请在针对 seen 进行测试之前删除扩展名:

extensions = ('.txt', '.foo', '.bar')
for dirpath, dirnames, filenames in os.walk(directory):
    for filename in filenames:
        if filename.endswith(extensions):
            root, ext = os.path.splitext(filename)
            if root in seen:  # we have seen this filename without extension already
                continue

            # do your thing
            seen.add(root)