Question about Column Sorting

[danwdoo]

Hello,
I've just started using Calibre and am simply amazed at how good it is. I have a hopefully simple question about column sorting. I have the following column Layout:

Author Series Title

Currently, I can sort by one column only. So while I can make the author's appear in alpha order, then the series column seems fairly random. Is there a way to sort by Multiple columns so I can have authors as first priority, then it sorts series within the authors and then by volume number?

Thanks!
Danny

[GeoffC]

Welcome Danny, there will be an expert along shortly ....

[WayneD]

I looked at the sorting code in database2.py, and it is always forcing the same secondary sort key if the entries in the requested sort column are the same. This apears to be the "path" data, which essentially gives you a sub-sort of the book title if the author is the same, or author if the title is the same, etc.

What I'd prefer to see is the sort function being allowed to return 0 when items are the same. Because python has a stable sort (one that keeps the current order when the sort term is found to be equal), this would let you choose your sub-sort by whatever column you had clicked previously. If you are comfortable editing source, this is as easy as editing the src/calibre/library/database2.py file, looking for the "def sort" function, commenting out the last 2 lines, and adding "return ans" to the end. The last 3 lines would then look like this:

        #if ans != 0: return ans
        #return cmp(self._data[x][11].lower(), self._data[y][11].lower())
        return ans

With that done, I can get click series and then author to see a primary sort by author with a sub-sort by series, and then click title and then author to see author with a sub-sort by title, etc.

[kovidgoyal]

will be in next release

[bwaldron]

Originally Posted by kovidgoyal

will be in next release

Nice!

[ilovejedd]

Originally Posted by kovidgoyal

will be in next release

Awesome. Thanks.

[danwdoo]

Excellent!

[WayneD]

One thing I thought of was that at startup time, we need to do two sorts in order to ensure that the user gets a nice sort order for something like author. The best solution is probably be to remember two most recent sorts the user did and rerun them both when refreshing the book list. Another is to do an initial sort by path and then apply the remembered sort (since that at least gets a remembered author sort to sub-sort by title instead of coming up in whatever order the DB returned the entries).

--- src/calibre/library/database2.py    2009-03-04 17:46:47 +0000
+++ src/calibre/library/database2.py    2009-03-05 15:21:33 +0000
@@ -256,6 +256,7 @@
         for r in temp:
             self._data[r[0]] = r
         self._map = [i[0] for i in self._data if i is not None]
+        self.sort('path', ascending)
         if field is not None:
             self.sort(field, ascending)
         self._map_filtered = list(self._map)

[kovidgoyal]

Doing a double sort on startup would be a major performance hit for people with large libraries. Instead I'll simply have restore the previous behavior for the first sort.