Q is a programming language created in 2003 by Arthur Whitney.
| #368on PLDB | 21Years Old | 768Repos |
Q is a proprietary array processing language developed by Arthur Whitney and commercialized by Kx Systems. The language serves as the query language for kdb+, a disk based and in-memory, column-based database. kdb+ is based upon K, a terse variant of APL. Read more on Wikipedia...
"Hello World"
/* Hello world in Q */
hello = writes "Hello, world!\n";dst:`:tq
src:`:tqsrc
F:key src
/ trade fields (types;widths) trf after 200609
tf:`time`ex`sym`s`cond`size`price`stop`corr`seq`cts`trf
tt:("TCSS*IFBIJCC ";9 1 6 10 4 9 11 1 2 16 1 1,1+20060930<"I"$-8#string first F)
/ quote fields (types;widths)
qf:`time`ex`sym`s`bid`bsize`ask`asize`cond`mmid`bex`aex`seq`bbo`qbbo`corr`cqs
qt:("TCSSFIFIC*CCJCCCC ";9 1 6 10 11 7 11 7 1 4 1 1 16 1 1 1 1 2)
/ sym[.s] "e"$pricebidask
g:{[f;x]`sym`time xcols delete s from @[;`sym;{$[null y;x;` sv x,y]}';x`s]@[x;f;"e"$%;1e4]}
foo:{[d;f;t;g;x]@[;`sym;`p#].Q.dsftg[(dst;"D"$-8#string x;d);(` sv src,x;sum t 1;0);f;t;g]}
\t foo[`trade;tf;tt;g[`price] ]each F where F like"taqtrade*[0-9]";
\t foo[`quote;qf;qt;g[`bid`ask]]each F where F like"taqquote*[0-9]";
\
http://www.nyxdata.com/Data-Products/Daily-TAQ
q)select from t where name like "ja*",age>50
name age
--------
jack 60
q)select rows:count i by age from t
age| rows
---| ----
20 | 1
50 | 2
60 | 1| Feature | Supported | Example | Token |
|---|---|---|---|
| Strings | ✓ | "Hello world" | " |