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Wiki editors are welcome. Anyone logged in as a GitHub user can edit. You do not need anyone’s permission to edit the wiki.
You can add anything you want to the wiki. Don’t worry about making it publication quality, just add it. You can even add informal notes you’ve taken. In fact, we’d appreciate it. If you’re not sure where to put something create a new page and link to it from the main page.
If you want to contribute but need help choosing something to work on there is always the issue list which is full of things that need improvement. Anyone may work on issues from the list.
If you do not find the information you are looking for about Kona on the web, two great places to ask are on either our Kona User or Kona Project Developer list (see below). These are open discussion lists without topic restrictions.
Please use a discussion list whenever possible instead of cold emailing an individual maintainer. All the maintainers will see your question on the discussion lists. The discussion list may give you more and faster information by giving more people a chance to answer. Answering questions on the mailing list lets us keep an archive to refer to people with similar questions in the future.
There are two discussion lists: kona-dev and kona-user. The dev/user divide is designed to split discussion between development on K and development with K.
Until the traffic warrants otherwise it is fine to talk about user issues on the dev list.
| Tutorial | Intro Screencast K 99: Ninety Nine K Problems Tutorial Verbs-Classification |
| Project Euler Code Golf: | Project Euler Code Golf |
| Project Coding Guidelines: | Coding Guidelines |
| List of idioms: | Idioms |
| Dictionaries: | Dictionaries |
| Strings: | Strings |
| Data and Execution: | Data and Execution |
| Primitive Operations | Primitive Operations |
| C Reference | C Reference |
| Examples | Examples |
| Memory Management | Memory Management |
| Amend | Amend |
| Random Lines of K | gist |
| Replicating SQL functionality | Replicating SQL functionality |
| shared library | shared library |
| more Memory management | newK, unpool, repool, kap |
| csv loading | csv loading and dictionary |
hakank’s K/Kona Page
Whitney on K
No Stinking Loops
Remarks on Style
K by example
K as a Prototyping Language
K on Rosetta Code
Kx Corporate Website
Kx K Examples
Gordon Baker’s Q site
Milan Ondrus’s KDB+ site
Introduction to K
kdbfaq blog
K 2.0 Reference Card [PDF]
FinnAPL Idioms
kdb faq on thalesians
Q for Mortals Book on Amazon
K 2.0 User Manual
K 2.0 Reference Manual
K 2.0 C-K Interface Manual
A+
J
kOS
Introduction to K
MapReduce in K
LinkedIn Group: [Kx] Technology Network [Jobs]
LinkedIn Group: KDB+/Q User Group
LinkedIn Group: Kx/KDB+ Networking Forum [Jobs]
Kx’s KDB+ Personal Developers Google Group
| Command | What It Does |
|---|---|
| \ | Shows ‘Help’ |
| .` | Shows the full K-Tree |
| Verb | Monadic | Dyadic | Triadic | Tetradic |
|---|---|---|---|---|
| + | flip | plus | ||
| – | negate | minus | ||
| * | first | times | ||
| % | reciprocal | divide | ||
| | | reverse | max_or | ||
| & | where | min_and | ||
| ^ | shape | power | ||
| ! | enumerate | rotate_mod | ||
| < | grade up | less_than | ||
| > | grade down | greater_than | ||
| = | group | equals | ||
| ~ | not/attribute | match | ||
| @ | atom | at index | amend/trap | amend |
| ? | range | function inverse/find | invert-guess | |
| _ | floor (tolerant) | drop_cut | ||
| , | enlist | join | ||
| # | count | take_reshape | ||
| $ | format | dollar | ||
| . | dot/monadic/make/unmake | dot index | amend/trap | amend |
| : | colon/monadic | colon/dyadic |
| Adverb | Definition |
|---|---|
| / | over |
| \ | scan |
| ’ | each |
| /: | each right |
| \: | each left |
| ’: | eachpair |
| Verb | Monadic | Dyadic |
|---|---|---|
| 0: | read text file. | write text file |
| read from stdin until EOF (empty symbol). | write to stdout if first param is an empty symbol ( `0:stuff_to_print ) | |
| 1: | read binary file (mmapped) | write binary file |
| 2: | read binary file (copied to memory) | dll function call |
| 3: | open handle/close handle | asynchronous send |
| 4: | type of data | synchronous send |
| 5: | printed representation | append to binary file |
| 6: | read raw byte string | write raw byte string |
| Name | Use | Example |
|---|---|---|
| : | :[\(cond_1;ret_1;cond_2;ret_2;\ldots;cond_n;ret_n;ret_{else}\)] | not_x: :[0=x;1;0] |
| if | if[\(cond;exp_1;exp_2;\ldots;exp_n\) ] | if[n!2; n:1+3*n; `0:"n was odd\n"] |
| while | while[\(cond; exp_1; exp_2;\ldots;exp_n \) ] | while[~a!2; a %: 2; `0:"dividing\n"] |
| do | do[\(n;exp_1;exp_2;\ldots;exp_m\)] | do[4; `0:"******\n"] |
| Command | Definition |
|---|---|
| \ | show help |
| \p [n] | [set] print precision |
| \r [seed] | [set] random seed |
| \+ | print operator reference |
| \l [script] | load k script |
| \s [script] | step k script |
| \t [code] | time execution (in ms) |
All reserved words start with a leading underscore(_)
| Name | Definition |
|---|---|
| _T | [current UTC Julian day count]+[fraction complete] (K epoch is 2035-01-01T00:00:00) |
| _a | program argument vector (argv) |
| _d | K-Tree path / current working dictionary |
| _f | anonymous reference to current function |
| _h | host name |
| _i | |
| _k | |
| _m | |
| _n | nil |
| _p | |
| _s | |
| _t | current UTC time (int) (K epoch is 2035-01-01T00:00:00) |
| _u | |
| _v | |
| _w |
| Name | Definition |
|---|---|
| _acos | inverse cosine |
| _asin | inverse sine |
| _atan | inverse tangent |
| _ceil | ceiling (intolerant) |
| _ceiling | ceiling (tolerant) |
| _cos | cosine |
| _cosh | hyperbolic cosine |
| _exp | exponential |
| _floor | largest previous integer (intolerant) |
| _log | natural logarithm |
| _sin | sine |
| _sinh | hyperbolic sine |
| _sqr | square |
| _sqrt | square root |
| _tan | tangent |
| _tanh | hyperbolic tangent |
| _abs | absolute value |
| _bd | convert to binary representation |
| _ci | char-of-int (octal if unprintable char) |
| _db | construct from binary representation |
| _dj | date from Julian day count |
| _exit | exit with status x |
| _getenv | get an environment variable |
| _gtime | in UTC, ints: YYYMMDD,HHMMSS (_gtime _t) |
| _host | host name IP address (int) |
| _ic | int-of-char |
| _inv | inverse of a matrix |
| _jd | Julian day count from date _jd 20110315 |
| _lt | convert output of _t to local time |
| _ltime | localized version of _gtime |
| _size | size of file (bytes) |
| Name | Definition |
|---|---|
| _bin | index of element using binary search |
| _binl | search for several elements |
| _di | delete element at index |
| _dot | dot product |
| _draw | draw x random numbers from 0 to y-1, negative y indicates without replacement |
| _dv | delete value |
| _dvl | delete several values |
| _in | true if x is in y |
| _lin | _in for several values |
| _lsq | matrix division |
| _mul | matrix multiplication |
| _setenv | set environment variable |
| _sm | string match |
| _ss | positions of substring y in string x |
| _sv | scalar from vector with base change |
| _vs | vector from scalar with base change |
| Name | Definition |
|---|---|
| _ssr | string search & replace |
| Name | Definition |
|---|---|
| -h (int) | open an HTTP port |
| -i (int) | open an IPC port |
| -e (string) | execute a string |
| -x (string) | execute a string and print |
| [file] | execute a script (as in ./k script.k, extension optional) |