Rutracker CSV split by subcategories

import os
import csv
import json

file = open('cats_subcats.json', 'r', encoding='UTF-8')
categories = json.loads(file.read())
file.close()

dirs = list(filter(os.path.isdir, os.listdir(os.getcwd())))
if(not os.path.isdir('shares/')): os.mkdir('shares/')

for category in categories:
    catpost = '/category_'+str(category['id'])+'.csv'
    shares = []

    for dirt in dirs:
        if(os.path.isfile(dirt+catpost)):
            file = open(dirt+catpost, 'r', encoding='UTF-8')
            shares.extend(list(csv.DictReader(file, fieldnames=('subcat_id', 'subcat_name', 'share_id', 'share_hash', 'share_name', 'share_size'), delimiter=';', quotechar='"')))
            file.close()

    for subcat in category['subcats']:
        subshares = {}
        for share in shares[:]:
            if(int(share['subcat_id']) == subcat['id']):
                subshares[share['share_id']] = {
                    'hash': share['share_hash'],
                    'name': share['share_name'],
                    'size': int(share['share_size'])
                }
                shares.remove(share)

        output = []
        for key in subshares: output.append({
            'id': int(key),
            'hash': subshares[key]['hash'],
            'name': subshares[key]['name'],
            'size': subshares[key]['size']
        })

        outname = 'shares/cat_'+str(category['id'])+'_subcat_'+str(subcat['id'])+'.json'
        if(os.path.isfile(outname)): os.remove(outname)
        outfile = open(outname, 'w', encoding='UTF-8')
        outfile.write(json.dumps(output, indent=4, sort_keys=True))
        outfile.close()