enumerate_styles.py

#!/usr/bin/env python3

# Collect a mapping of style -> appearances
appearances = {}
for i in range(1, 51):
    with open(f'[Treebeard] Kemono no Souja Erin BD - {i:02}.ass', 'r') as f:
        for line in f:
            if line.startswith('Style:'):
                line = line.strip() # Get rid of stray newlines
                line = line[7:] # And the Style: prefix
                if line not in appearances:
                    appearances[line] = []
                appearances[line].append(i)

# Collect a mapping of appearances -> styles
categories = {}
for style, eps in appearances.items():
    eps = tuple(eps) # Python dictionary keys need to be immutable
    if eps not in categories:
        categories[eps] = []
    categories[eps].append(style)

# input: [1, 2, 3, 5, 6, 8, 10, 11, 12, 13]
# output: [[1, 3], [5, 6], [8, 8], [10, 13]]
def groups_from_eps(eps):
    groups = [[eps[0], eps[0]]]
    for ep in eps[1:]:
        if ep == 1 + groups[-1][1]:
            groups[-1][1] = ep
        else:
            groups.append([ep, ep])
    return groups

# input: [5, 5] or [6, 20]
# output: '05' or '06-20'
str_from_group = lambda group: f'{group[0]:02}' if group[0] == group[1] else f'{group[0]:02}-{group[1]:02}'

# input: [[1, 3], [5, 6], [8, 8], [10, 13]]
# output: '01-03, 05-06, 08, 10-13'
str_from_groups = lambda groups: ', '.join(str_from_group(g) for g in groups)

# input: [1, 2, 3, 5, 6, 8, 10, 11, 12, 13]
# output: '01-03, 05-06, 08, 10-13'
str_from_eps = lambda eps: str_from_groups(groups_from_eps(eps))

for eps in sorted(categories.keys(), key=len, reverse=True):
    print(str_from_eps(eps) + ':')
    for style in categories[eps]:
        print('\t' + style)