Brian, I haven't read your report below closely, but bear in mind that the code I posted assumes pages are counted from zero. In fact, it enforces this assumption by converting "foo.png" explicitly to "foo 0.png".
I also didn't get a chance to look into the earlier report about out-of-order indices, though I'm quite surprised that explicit sorting was required to fix it. My goal in designing (|@:- 2&| * (- 2&|)@#) and earlier versions was specifically to create a purely arithmetic, ordering-independent function. In other words I set out to define a scalar dyad, which, given the input page number and the total number of pages in the book, would produce the corrected page # for odd pages. That it requires the input _array_ to be sorted confuses me: except for the #, none of its components can even see the "array", per se (only the individual scalars). BTW, that # is the first place you should look to permit one-based page numbering. -Dan PS: The reason the rest of the code is "so clear" vs np is because the focus of my effort was a compact, elegant way to express np. The rest of the verb was just stamp-collecting (so I didn't focus on making it "interesting" :) . I'm sure there are straightforward but unexciting ways to express the core page flipping verb, particularly at rank 1 . -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brian Schott Sent: Sunday, December 22, 2013 3:20 PM To: Chat forum Subject: Re: [Jchat] Fwd: Archive j I thought the verb flipOddPages worked, but the reversing of odd pages line works for neither an odd nor an even number of pages. Let me demonstrate with the verbs I defined in my construction early in this thread. NB. argument is an integer indicating number of pages in a report nodd=: >.@-: neven=: <.@-: odd=: >:@+:@i.@nodd even=: 2+|.@:+:@i.@neven zero=: '0'&,@":"0 (,.@i.;zero@ (odd,even)"0) ] 5 ┌─┬──┐ │0│01│ │1│03│ │2│05│ │3│04│ │4│02│ └─┴──┘ (,.@i.;zero@ (odd,even)"0) ] 6 ┌─┬──┐ │0│01│ │1│03│ │2│05│ │3│06│ │4│04│ │5│02│ └─┴──┘ In contrast to the above, with the code that "reverses order of odds" in the verb `flipOddPages` I get the following results below (which I cannot make agree with the above). (+ 2&| * #-+:) i. 6 0 5 2 3 4 1 >: (+ 2&| * #-+:) i. 6 NB. same as above, but adding 1 1 6 3 4 5 2 (|@:- 2&| * (- 2&|)@#) i. 6 0 5 2 3 4 1 (|@:- 2&| * (- 2&|)@#) i. 5 0 3 2 1 4 Actually, to make the verbs `odd` and `even` above work with the order of the files in my Mac directory, rather than with the indices 0, 1, 2, .. , the examples above need to be as follows, where the boxes are rotated to correspond to the order of the filenames in the directory/ (,.@i.;&(1&|.)zero@ (odd,even)"0) ] 5 +-+--+ |1|03| |2|05| |3|04| |4|02| |0|01| +-+--+ (,.@i.;&(1&|.)zero@ (odd,even)"0) ] 6 +-+--+ |1|03| |2|05| |3|06| |4|04| |5|02| |0|01| +-+--+ I suspect I can make this work on my own because the rest of the code is so clear, but I am keeping the discussion open if anyone is keeping up. I hope I am not wrong in my assessment here, but I do have a less than stellar history, and may be quite wrong. Thanks, On Mon, Dec 16, 2013 at 6:51 AM, Dan Bron <[email protected]> wrote: > Sorry, I should have tested my code on odd-length arguments as well as > even. > > > Thanks to Raul's help on twitter, we can fix the bug by using (|@:- > 2&| * > (- > 2&|)@#) in place of (+ 2&| * #-+:) . > > To address the '\' vs '/' issue, I suppose we should standardize by > using PATHJSEP_j_ (or PATHSEP_j_ in J6-) in place of raw '\'. > > I'm not sure what changes to make to the verb, if any, to get it to > work properly on the example directory you gave. I suspect you're > getting blank output because it's not scanning the directory you want > it to. I suggest you embed a line like > > smoutput jpath dir,pfx,'*.',sfx > > somewhere in the verb, to see what directory J's looking in. If the > directory looks right, but you're still getting blank output, then the > filename pattern may be wrong. > > If the directory doesn't look right, remember that ~ is being expanded > by jpath, not your shell. In your shell, ~ means "home", i.e. your > user directory. In J, it means your "J home", which is often a > subdirectory of your user directory. Try using an absolute path > (starting with '/') to force J to look in the right place. If that > works, you can experiment with jpath and USERFOLDERS to figure out if you can > use a shorter synonym. > > If the directory looks right, but the pattern doesn't, then you can > try experimenting with the LHA to flipOddPages. By default, the verb > will look for files using the pattern 'comb*.png'. You can adjust > either the prefix > ('comb') or the suffix ('png') or both, using the x argument. > > For example, in your original message, you listed a number of files > whose names started with 'combined', (as in 'combined 4.png'), so you could > say: > > 'combined' flipOddPages some_directory > > You also discussed generating PDFs instead of PNG files; in that case, > you could say: > > 'combined pdf' flipOddPages some_directory > > or > > ('combined';'pdf') flipOddPages some_directory > > In any case, I don't think we're far off. Should just take some > experimentation and maybe a few adjustments to the code. > > -Dan > > > flipOddPages=:verb define > 'comb png' flipOddPages y > : > NB.y=directory to scan, x=file prefix and suffix > 'pfx sfx'=.2 {. (;:^:(0=L.) x),<'png' > dir =. (,PATHJSEP_j_-.{:)y NB. Use PATHSEP_j_ in J6 and earlier > versions > > smoutput jpath dir,pfx,'*.',sfx > > NB. Scan directory > fn =. {. |: 1!:0 jpath dir,pfx,'*',sfx > > NB. Zero-fill here will convert comb.png to comb 0.png > NB. The increments account for the space after comb and > NB. the dot before png respectively. > pn=.0 ".&> (1+#pfx) }.&.> (-1+#sfx)}.&.> fn > > NB. Reverse order of odds > pn=. (|@:- 2&| * (- 2&|)@#) pn NB. ************* > > NB. Table of old-filename, new-filename > fn ,. <@;"1 (<pfx,' '),.(":&.> pn),.<'.',sfx > ) > NB. Can remove smoutput line once you're done debugging > > NB. Usage examples: > flipOddPages '~temp\archive1' > 'combined' flipOddPages '~temp\archive1' > 'combined pdf' flipOddPages '~temp\archive1' > ('combined';'pdf') flipOddPages '~temp\archive1' > > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Brian Schott > Sent: Saturday, December 14, 2013 1:17 PM > To: Chat forum > Subject: Re: [Jchat] Fwd: Archive j > > Raul and Dan, > > Yes, when I change '\' to '/' Dan's flipOddPages works great in my j > temp folder. I am struggling making it work in a folder like the one I > showed, but that is temporary, I hope. When I do, I get a blank line output. > > I also want to see how to deal with an odd number of pages. > > Great app, though. > > Thanks, again. > > > -- > (B=) > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- (B=) <-----my sig Brian Schott ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
