Cities

blah.R

library(tidyverse)
library(stringi)
library(stringr)

df <- tibble::tribble(
  ~id, ~response,
  1, "Paris to Berlin blah blah blah",
  2, "Hello there stuff berlin London to Madrid berlini-Stuff Dover",
  3, "Białystok to Port-au-Prince",
  4, "I went to Saudi",
  5, "I went to Saudi arabia"
)

cities <- c("Paris", "Berlin", "London", "Madrid", "Dover(-Foxcroft)?",
            "Bialystok", "Port-au-Prince", "Beijing", "Saudi( Arabia)?")

codes_rex <- "\\b(BOS|CDG|LAX)((?:-(BOS|CDG|LAX))+)\\b"

stri_match_all_regex("BOS-CDG-LAX and other stuff", codes_rex)

cities_rx <- str_c("(?i)\\b(", str_c(cities, collapse = "|"), ")\\b")

df_ <- df %>% 
  mutate(response = stri_trans_general(response, "latin-ascii")) %>%
  mutate(cities = str_extract_all(response, cities_rx)) %>%
  select(id, cities) %>%
  unnest %>%
  mutate(cities = str_to_title(cities))