You are welcome, it is my pleasure to help you if I can. Even if speed is not your concern (it was for me, having to deal with very large files, several GB), the post I linked to offers 8 different solutions to your problem (3 of which, at least, perhaps more, were suggested by other monks in previous posts of the same thread, you can look at the history of the thread if you want to know; well, in brief, they are not "my" solutions, but solutions derived from a very fruitful discussion with many monks), you may find some interesting ideas from them.