In
Generating Library Statistics Reports? (now locked) I made the comment...
I do use [a Category View] occasionally when I want something more in the form of a statistical summary than a Panes View can provide. I would use it much more for that purpose if it didn't have one very limiting behaviour. That is, there's no way to select 'all' of a given category. So if I include [Decade] as a category, then I will get a summary of everything—or the last selected category value (e.g., one genre)—by decade. But then I must select a decade to go any further—so any further statistics are for that one decade only. I can, of course, revise the view to remove [Decade] or place it elsewhere in the sequence of categories included. But that ruins the otherwise dynamic nature of the report.
I just had a doh! moment as the simple solution dawned on me. Instead of defining the categories with fields, use expressions that include 'All'. Doing so is as easy as replacing [Genre], for example, with
[Genre]; All&DataType=[List]. If my categories are Genre - Style - Decade - Artist - Album, I'm no longer stuck having to choose a value in each category. This means, for example, I can select Rock - ALL - 1970 and get a set of statistics (albums, tracks, duration, average number of plays) for each Style of Rock from the 1970's. The 'All' value, of course, shows the total for the group (in this case, the Rock Genre).
Another 'trick' that goes nicely with this is to include as the first category a
Playlist Group that includes all Audio Playlists. One of those playlists should include all audio files—to ensure including the category does not restrict the files that may appear in the view. I've included it as a category twice to provide a means of combining two playlists. My 'All Audio' playlist is in the root folder of the group, so it can be selected easily to skip the category. One very handy playlist is [Track #]=[1] which effectively turns the view into a list of albums with [Track #] in the Categories pane showing the number of albums for whatever categories have been displayed.
As I indicated in my original post, I think this was the only barrier to such view serving reasonably well as a fully dynamic statistics report—short of pretty charts and graphs. Things like 'Top Ten Lists' aren't really necessary when they can be viewed for any measure (number of files, total duration, average number plays, etc.) just by sorting the list of categories. The list, of course, will always show the details of whatever category is selected—something a simple statistical summary cannot do.