Redundant Local Files

[user-removed]

Over the years I have built up a big library of local files.  Importing these into Spotify is slow and probably in most cases unnecessary:  is there an easy way to cull out those songs which are available for streaming in Spotify?  I have some music that Spotify doesn't have (and likely never will) and it would seem to make sense to put these songs/albums in a folder or drive that I can then import into Spotify (and therefore not import stuff which Spotify does have).  Suggestions?

Thank you.