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Questions tagged [q-lang]

The q language is a programming language by kx.com for querying kdb+ databases.

Q was developed by Arthur Whitney in 2003 and is built on top of the K programming language. The names q and kdb+ are often used interchangeably, but generally q refers to the programming language and kdb+ refers to the entire runtime environment.

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kdb/q update a keyed table element's list element

I have a table like: q)tbl[`XXX] 1977 1987 1997 and I want to update the nth element from the list of years, so the above becomes q)tbl[`XXX] 1997 1987 2007 And need it to be inplace? Been looking into the docs but having hard figuring it out.
Alim Hasanov
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[KDB+/Q]: (Re-)define view programmatically (dynamically)

I can define view either by loading a q script, or interactively from console: q)myview::a+b / even semi-programmatically using ugly strings: value"myview::a+b" Some exploration: q)value `. `myview :: (+;`a;`b) `a`b "a+b" I can see…
Daniel Krizian
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Trying to aggregate by mean and then trim outliers of observations based on the mean in kdb

I'm trying to find the average value by item type, and then set a variable y that takes the value: missing value if x = 0, y = x. Then round values that are too big or too small: if x > 0, x > mu, then set y = mu if x < 0, x < mu, then set y =…
user7613376
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Add q/kdb Build System to Sublime 3

I am using Sublime Text 3 (on Mac OS) and would like to add a q/kdb build to it so I can run the q code directly from ST. I have the below build file: { "cmd": ["/Users/XXX/q/m32/q", "-u", "$file"], "file_regex": "^[ ]*File \"(...*?)\", line…
Alim Hasanov
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How to change namespace by parameter in KDB+

I want to change namespace by a given parameter something like below: f:{system "d x"} but this failed, .i.e q)f[".new"] {system "d x"} '" @ .,["\\"] "d x" How can I do this? Thanks.
Rongshu
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kdb+ : Command Line parameter as a filename to be saved as

How do I parse a command line parameter and use it as a variable in the script to be used as filename to be saved as. I have tried the below but it is not working fname:.z.X[2] ..... ...more code... .... /Save the table into a csv…
Alim Hasanov
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kdb+ : concatenate table elements into a third column

I have this: a b c "aa" "bb" "cc" "aaa" "bbb" "ccc" I want to end up with -,|,/,\ in between or any other third string: a b c ab "aa" "bb" "cc" "aa-bb" "aaa" "bbb" "ccc" ""aaa-bbb" for example
Alim Hasanov
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[KDB+/Q]: Manipulate parse tree of a function (`inverse` combinator)

How to extract and manipulate parse tree of a lambda/function? E.g. given the function pair:{` sv x,y}' I'd like to arrive at the "inverse" version using a combinator called inverse so that the following call returns (note the now swapped order of…
Daniel Krizian
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upsert into unkeyed kdb table

I am trying to modify the entry in the factor column that corresponds to the provided date. I cannot find any good documentation for KDB's upsert function and I have zero idea what I am doing wrong here.. query: {[table;dates;factors] table upsert…
jono
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Finding position of key in list column of a table

I have a table with one of columns keyname being int and another column keylist being list of int. I am trying to create another column which is position of keyname in keylist in my table in following manner: update keypos:{y?x} . (keyname;keylist)…
Rahul
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Regex syntax for support q/k/kdb+ comment using JLexer

Q: What do I need using for my lexer logic? Only regex or maybe special functions of lexer? Where does the mistake in my syntax for q multi-comment? Details: I'm trying to write intellij idea plugin for k/q/kdb+ (wiki, q/kdb+), and my plugin based…
Alykoff Gali
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select from with wildcard, in Q KDB

I use KDB with a tool that let me set queries. With this tool, only the parameters (filter value) can be changed with user interaction, not the structure of the query. I need a query to be run on user action. By default, I want it to select every…
Sithered
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Tickperplant subscription by sym sending single records not tables by editing .u.pub

I have a ticker plant that has the schema: quote:([]time:(); sym:();expiration:();mtype:();price:();cond:();exchange:();volume:()) trade:([]time:();…
Rtrader
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How to save what I have selected into a new table in KDB

I have selected something in a table how to put what I have selected into a new table? Select code is like: select vwap:(sum PRICE*VOLUME)%(sum VOLUME) by SYMBOL,DATE from trade
Chao Zhu
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How to apply a function to an entire column?

I have the following table from a JDBC connection in Q. q)r some_int this created_at updated_at .. -----------------------------------------------------------------------------.. 1231231 "ASD"…
Istvan
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