mets.str <- c("Spotify_Plays_d", "iTunes_AlbumSales_Net__d", "iTunes_AlbumUnits_Net__d", "iTunes_TrackSales_Net__d", 
                "iTunes_TrackUnits_Net__d", "iTunes_VideoSales_Net__d", "iTunes_VideoUnits_Net__d")

  mets.nms <- substr(mets.str, 1, 15)


  # Add prefix
  pfx <- "aft.avg."
  metspre <- paste0(pfx, mets.str)

  # This is how we evaluate
  v3[, lapply(eval(metspre), function(x) get(x, envir=parent.frame(2))) ]

  # THIS IS HOW WE NAME IT!!
  v3[, {tmp <- lapply(eval(metsbfr), function(x) get(x, envir=parent.frame(2))); names(tmp) <- mets.nms; as.list(tmp)} ]  [1:5, 1:4, with=FALSE]