df %<>% distinct(notificationNumber, lot_id, product_id, .keep_all = TRUE)

  df$okpd2 %<>% as.factor
  df %<>%
    mutate(
      etp = ifelse(is.na(etp), "unknown", etp),
      okpd2_head = substr(okpd2, 1, 2),
      okpd2_group = substr(okpd2, 1, 5),
      okpd2_type = substr(okpd2, 1, 8)
    )

  count_lot <- df %>%
    group_by(lot_id) %>%
    summarise(count = n_distinct(product_id))

  df %<>%
    group_by(lot_id) %>%
    mutate(
      main_okpd2_class = MaxTable(okpd2_head),
      main_okpd2_group = MaxTable(okpd2_group),
      main_okpd2_type = MaxTable(okpd2_type),
      main_okpd2_subcat = MaxTable(okpd2)
    ) %>% ungroup()

  df %<>% left_join(count_lot)