#!/usr/bin/python cart = [ {'id': 1, 'name': 'Product1', 'price': '2000', 'quantity': 0}, {'id': 2, 'name': 'Product2', 'price': '3000', 'quantity': 0}, {'id': 3, 'name': 'Product3', 'price': '4000', 'quantity': 0} ] print cart readed = {'id': 1, 'name': 'Product1', 'price': '2000', 'quantity': 0} print readed index = cart.index(readed) print index cart[index]['quantity'] += 1 print cart