9 ms·

The free version of K can be downloaded at http://kx.com/software-download.php http://kx.com/software-download.php

• akkartik 12y ago
  But it doesn't look like that version can run edit.k from kparc.com. So for all practical purposes kx.com and kparc.com are distinct languages/dialects. Edit: I should clarify that I'm trying to make sense of the specific code in the OP, in particular to play with the views idea (the :: operator). I should have probably put this thread under https://news.ycombinator.com/item?id=8743325 https://news.ycombinator.com/item?id=8743325
  • cturner 12y ago
    Yeah, I tried the same and came to same conclusions. Someone who knew what they were doing could implement a new-k impl from the lang def on kparc. That is all you would need. Alas, I am not that guy.
  • geocar 12y ago
    kOS is K5; it's as different from K4 as K4 was to K3. Views are available in K4/Q/KDB+, so the version on kx.com does work with views. If you want to play with the views idea, try to solve a problem and see where a view helps you. Here's one I did earlier this week; I've got this tool that takes a whole bunch of logfiles of userids and counts; they look like this: 5033703751425413371 1 5409789758109122623 4 10102846067816284236 4 I call these columns `s(sessionid) and `c(count); I can load them with this: G:{g::select from(+`s`c!("*I";" ")0:"S"$":",x) where (c>0)} Now I say something like: G"trk/tnl5/20141207/TRK_ITM" to get one of these structures into the g variable. I actually have a bunch of filenames: t:{R:{(x,"/"),/:$:!"S"$":",x};,/R',/R'R"trk"}[] So I can load the first one with: G t 0 This is convenient, since these files are big (1Gb each or so) I'll want to work with a subset: g:10000#g This isn't part of my program, it's just something I do while developing. If I run "G" again it'll get the entire file again. Now, I want to match these against another list of users. I'll do a similar trick: D:{d::0:"S"$":",x} and now I can do: D"users.txt" to put this into the d variable. My program needs to find the rows of g that d match. Some of the sessionids in the logfiles are corrupt. They look like this instead: 7241110807448127691320303160517889791474867567241110807448127691320312936057606400732600664532969577042775 4 62349552899220301013203170219134834182361546234955289922030101320303170219134834182361546234955289922030101 4 These are wrong. I originally tried to figure out them by finding the longest string that was also at the beginning of the sessionid, but after talking it out with Oleg and Pierre I decided to try to simply match them against the lengths of d: ?:#:'d said I only have two lengths (19 and 20), so this is a much smaller search than what I was trying before! To do this, I used views: K::?:#:'d k::"S"$"S",/:$:'K f::k!+(K#\:/:g.s) Now f is an index on g; instead of a `s column it has an `Sn column where n is length of the key; i.e. I have a `S19 and an `S20 column with the first 19 characters of `s and the first 20 characters of `s accordingly. s::g.s[&|/f[k]in\:d] c::g.c[&|/f[k]in\:d] Now I can look at the `s and `c vars and do what I want to do; get my unique userids and my counts. More importantly, I can apply this to all my files (I have a lot of them): n:0;m:0;{G x;n+:+/c;m+:+/g.c}'t