Whenever you see this pattern, think of using a generator instead: def read_portfolio(filename): with open(filename) as f: rows = csv.r

Whenever you see this pattern, think of using a generator instead: def read_portfolio(filename): with open(filename) as f: rows = csv.reader(f) headers = next(rows) for row in rows: yield { 'name' : row[0], 'shares' : int(row[1]), 'price' : float(row[2]), } Now you can call read_portfolio() to get an iterable that lazily reads the file and yields dicts: portfolio = read_portfolio() for record in portfolio: print '{shares} shares of {name} at ${price}'.format_map(record)