Rutracker CSV category list exporter

import os
import csv
import json
from operator import itemgetter

def read_cats(filename):
    file = open(filename, 'r', encoding='UTF-8')
    categories = list(csv.DictReader(file, fieldnames=('id', 'name', 'filename'), delimiter=';', quotechar='"'))
    file.close()

    for category in categories: del(category['filename'])
    return sorted(categories, key=itemgetter('name'))

def get_subcats(id, dirs):
    subcats = {}
    for dirt in dirs:
        if(os.path.isfile(dirt+'/category_'+id+'.csv')):
            file = open(dirt+'/category_'+id+'.csv', 'r', encoding='UTF-8')
            shares = list(csv.DictReader(file, fieldnames=('subcat_id', 'subcat_name', 'share_id', 'share_hash', 'share_name', 'share_size'), delimiter=';', quotechar='"'))
            file.close()
            for share in shares: subcats[share['subcat_id']] = share['subcat_name']

    result = []
    for key in subcats: result.append({
        'id': int(key),
        'name': subcats[key]
    })
    return sorted(result, key=itemgetter('name'))

cats = read_cats('category_info.csv')
dirs = list(filter(os.path.isdir, os.listdir(os.getcwd())))
for cat in cats: cat['subcats'] = get_subcats(cat['id'], dirs)

if(os.path.isfile('cats_subcats.json')): os.remove('cats_subcats.json')
outfile = open('cats_subcats.json', 'w', encoding='UTF-8')
outfile.write(json.dumps(cats, indent=4, sort_keys=True))
outfile.close()