Looking for a way to list various image sequences in a directory in Python

Question

I have a directory with some image sequences that follow a similar naming convention, for example: test.1001.exr, test.1002.exr, test.1001.dpx, test.1002.dpx.

I'm trying to write some code that would output the following:

test.1001-1002.exr

test.1001-1002.exr

I found an example which does list them in the way I would like, however it is not very robust and would not show the file extension unless I print the specific one.

    scans = []

    for root, dirnames, filenames in os.walk(scanDir):
        for file in filenames:
            for ext in fileFormats:
                if ext in file:
                    scans.append(file)

    scans = [os.path.splitext(file)[0] for file in scans]
    scans.sort()

    def extract_number(name):
        return re.findall(r"\d+$", name)[0]

    def collapse_group(group):
        if len(group) == 1:
            return group[0][1]  # Unique names collapse to themselves.
        first = extract_number(group[0][1])  # Fetch range
        last = extract_number(group[-1][1])  # of this group.
        length = len(str(int(last)))
        return "%s%s-%s%s" % (group[0][1][:-length],
            first[-length:], last[-length:], ".dpx")

    groups = [collapse_group(tuple(group)) \
        for key, group in itertools.groupby(enumerate(scans),
            lambda index_name: index_name[0] - int(extract_number(index_name[1])))]
else:
    groups = []

I'm not sure I'm able to modify the code to achieve my result. Does anyone know a way I can do this?