How can I sort a column so 'empty' fields are last?

capnm · 02-06-2017, 10:27 PM

I'd like to be able to sort a custom column so I see the entries in ascending alpha-numeric order with the blank entries last.

It's a column created from other columns via template programming, so I can put whatever value I want in the 'blank' entries.

The obvious solution would be to use a whitespace character that sorts past 'z' in the sorting sequence, but I don't know if there is such a character. (Actually I haven't been able to figure out precisely what collation sequences Calibre uses.)

I'd even settle for a nearly invisible character if that's the best I can do.

Thoughts anyone?

p.s. I'm on Windows 10, which may or may not make a difference.

kovidgoyal · 02-06-2017, 10:33 PM

calibre uses ICU language based collation rules. I dont recall what they do with all the various unicode space characters, but I'd start looking there.

capnm · 02-06-2017, 11:14 PM

Well .... that's what I was trying to do, but got lost.
Actually, I was looking at the collation charts at unicode.org, but I'm not sure if that's where I should be looking.

I'm wondering if it sorts all the punctuation/symbols before the digits, before the alpha characters. The unicode site isn't really clear (to me) about that.

kovidgoyal · 02-06-2017, 11:50 PM

Just try it with a few of the unicode space characters starting with a simple space, then using non-breaking space, quarter, space, half space, double space etc, etc.

capnm · 02-07-2017, 12:08 AM

Tried that without any luck.
I was hoping I missed something obvious, or that someone else had done it already.
Guess not.

Thanks for the quick response, though!

02-06-2017, 10:27 PM	#1
capnm Groupie Posts: 156 Karma: 10001 Join Date: Feb 2011 Device: sony	How can I sort a column so 'empty' fields are last? I'd like to be able to sort a custom column so I see the entries in ascending alpha-numeric order with the blank entries last. It's a column created from other columns via template programming, so I can put whatever value I want in the 'blank' entries. The obvious solution would be to use a whitespace character that sorts past 'z' in the sorting sequence, but I don't know if there is such a character. (Actually I haven't been able to figure out precisely what collation sequences Calibre uses.) I'd even settle for a nearly invisible character if that's the best I can do. Thoughts anyone? p.s. I'm on Windows 10, which may or may not make a difference. Last edited by capnm; 02-06-2017 at 11:32 PM.

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02-06-2017, 10:33 PM	#2
kovidgoyal creator of calibre Posts: 43,859 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	calibre uses ICU language based collation rules. I dont recall what they do with all the various unicode space characters, but I'd start looking there.

02-06-2017, 11:14 PM	#3
capnm Groupie Posts: 156 Karma: 10001 Join Date: Feb 2011 Device: sony	Well .... that's what I was trying to do, but got lost. Actually, I was looking at the collation charts at unicode.org, but I'm not sure if that's where I should be looking. I'm wondering if it sorts all the punctuation/symbols before the digits, before the alpha characters. The unicode site isn't really clear (to me) about that.

02-06-2017, 11:50 PM	#4
kovidgoyal creator of calibre Posts: 43,859 Karma: 22666666 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Just try it with a few of the unicode space characters starting with a simple space, then using non-breaking space, quarter, space, half space, double space etc, etc.

02-07-2017, 12:08 AM	#5
capnm Groupie Posts: 156 Karma: 10001 Join Date: Feb 2011 Device: sony	Tried that without any luck. I was hoping I missed something obvious, or that someone else had done it already. Guess not. Thanks for the quick response, though!

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