Hey Alex, What I need is an "and" - with collects, I do a (sect of L1 L2) ... I tried a bunch but cant seem to get "and" working - I need the items that are "RED" and "BLUE" :( Perhaps I have to adjust the ER to achieve this? regards, Kashyap
On Tue, Nov 26, 2019 at 7:42 AM C K Kashyap <ckkash...@gmail.com> wrote: > Thanks Alex, > I'll try it out. > Regards, > Kashyap > > On Mon, Nov 25, 2019 at 11:24 PM Alexander Burger <a...@software-lab.de> > wrote: > >> Hi Kashyap, >> >> > Here's a new problem - as per the previous conversation, it seems that I >> > could use "collect" to get the items that I am interested in. >> > >> > (let (RED (db 'nm '+TagVal "RED") >> > BLUE (db 'nm '+TagVal "BLUE")) >> > (setq L1 (collect 'v '+Tag RED RED 'itm)) >> > (setq L2 (collect 'v '+Tag BLUE BLUE 'itm))) >> > (sect L1 L2) --> this is what I want >> > It looks like the step> method of QueryChart calls "prove" which tells >> me >> > that it can only do pilog. >> >> Yes +QueryChart needs Pilog. In general, Pilog is also recommended if the >> possible result set may be large and long 'collect'ed lists become >> inefficient. >> >> So the 'v' index of '+Tag' needs to be traversed twice, once for the RED >> object >> and once for BLUE. >> >> To do the above in Pilog, you need a combined generator and a filter with >> 'or': >> >> ... >> @Col1 (db 'nm '+TagVal "RED") >> @Col2 (db 'nm '+TagVal "BLUE") >> ... >> (select (@Tag) >> (... >> ((v +Tag @Col1 v +Tag @Col2)) # Traverse tree twice >> ... ) >> (or ((same @Col1 @Tag v)) ((same @Col2 @Tag v))) # filter with OR >> ... ) >> >> or generate directly >> >> ... >> @Col1 "RED" >> @Col2 "BLUE" >> ... >> (select (@Tag) >> (... >> ((nm +TagVal @Col1 nm +TagVal @Col2) (v +Tag)) >> ... ) >> (or ((same @Col1 @Tag v nm)) ((same @Col2 @Tag v nm))) >> ... ) >> >> (Not tested!) >> >> ☺/ A!ex >> >> -- >> UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe >> >
