Parsing txt file

Well, I would have done it like this if I understood the question correctly and if I need to save to the file:

 in_file = "IN.txt" out_file = "OUT.txt" data_file = [] # Открыли, прочитали, получили список with open(in_file, 'r') as read_file: for line in read_file: data_file.append(line.strip('\n')) # Соединили из списка в строку, записали построчно with open(out_file, 'a') as save_file: tmp_string = '' for num, line in enumerate(data_file): if num % 2 == 0: tmp_string = line continue else: result = '%s - %s\n' % (tmp_string, line) save_file.write(result) 

But this is if the lines go one by one in order and never change. Those. is always:

 a "text" b "text" 

The result will be:

 a "text" - b "text" a "text" - b "text" 

If there is also a c "text":

 in_file = "IN.txt" out_file = "OUT.txt" data_file = [] # Открываем и парсим файл with open(in_file, 'r') as read_file: tmp_string = '' # Перебираем файл по строкам и сравниваем начальный символы строки for line in read_file: my_string = line.strip('\n') if my_string[0] == "c": data_file.append(my_string) if my_string[0] == "a": tmp_string = my_string if my_string[0] == "b": tmp_string = '%s - %s' % (tmp_string, my_string) data_file.append(tmp_string) tmp_string = '' # Сохраняем в новом файле with open(out_file, 'a') as save_file: for line in data_file: save_file.write('%s\n' % line) 

Of

 c "text" a "text" b "text" a "text" b "text" c "text" 

We get:

 c "text" a "text" - b "text" a "text" - b "text" c "text"