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The Array Cast

For our first episode, host Conor Hoekstra talks to Adám Brudzewsky of Dyalog Ltd., Stephen Taylor, the KX Librarian, and Bob Therriault, a J enthusiast, about the qualities of the array languages that they enjoy.arraycast.comStephen Taylor | Librari...

SJT by New Contributor
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From loops to vectors

In learning q most of us have to drop the habit of edging into a solution with loops and think instead of vector operations. The transition is typically both awkward and exhilarating. It is harder if you are a solo student without vector-savvy collea...

SJT by New Contributor
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.Q.gz?

Hi,I sent an email before asking about .Q.gz I wanted to follow up on. (The email is not yet posted).I was able to use the qgz library so I think that should suffice. I'm still not sure about .Q.gz from documentation. Is it only in 4.0 and not in 3.6...

Angela by New Contributor
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.Q.gz ?

Hi,I can't get ".Q.gz"? https://code.kx.com/q/ref/dotq/#qgz-gzipq).Q.gz'.Q.gz [0] .Q.gz ^I'm on Ubuntu (wsl 2). I did install 32 bit zlib ("sudo apt-get install zlib1g-dev:i386") though I'm uncertain if I'm using the right one or setting it up correc...

Angela by New Contributor
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Issue in deserializing in q from c++

Hello, wondering if anyone has any ideas here I have been trying to publish a serialized K object from C++ using Kafka, and trying to deserialize using kdb/q (using -9!msg[`data]) on a kafka q topic listener. I am able to serialize/deserialize simple...

Re: [personal kdb+] dictionary with flip

as you point out, tables are stored in memory as a flipped dictionary of lists:show t:flip `name`iq!(`Dent`Beeblebrox`Prefect;98 42 126)name iq --------------Dent 98 Beeblebrox 42 Prefect 126but you can treat a table as a list of dictionaries (and in...

Nick by New Contributor
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higher-order function with recursive

Hi All,I am new to KDB+ and q. I am trying implement higher-order function with recursive and found below code in the docs.I could not understand how it is working.Could you please explain below code.codeq) 10 {x,sum -2#x}/ 1 1results1 1 2 3 5 8 13 2...

Big Integers (larger than long)

Anyone know how to handle numbers larger than long in kdb+?I need to handle numbers with 20+ digits in kdb+. It seems there is no inbuilt data types for this, other than to store the number as a string or hex. Does anyone know any KDB+ libraries to d...

How to replace first n entries in a column with 0N

Hi, I am running a calculation and I want to replace my first n entries in the row with empty value. How should I do that?i.e, mycol mycol -------------------- to --------------------- a 0N b 0N c c d dThank you so much for your help!Emily -

How to calculate correlation every few rows

Hi All,I have a table which looks like this:num sym1 sym2 sym3. sym4-----------------------------------------------------------------1 1.5 -0.1. 9.4. 3.12 2.5 - 0.9 3.1 0.53 5.4 2.9. -0.3. 1.04 0.5 0.1. -0.4. 1.45 0.3 0.0 3.6. 0.4How can I calculate ...

Question about linux-arm version for Raspberry Pi

Hi every, just found this great place.I recently got a rasp pi with 8GB memory. I heard about KDB is extremely fast, and I hope to do some web crawling stuff with the rasp PI. I have two questions:1. should I run linux arm version for 32 bit? I tried...

Question about fncol function in dbmaint

HI all, it can apply some function to a column, but if it possible to apply some function to selected records of a column? Do something like "update price*2 from trade where sym=xxx", is that possible?

carfield1 by New Contributor
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Function within a function

I am struggling with how to map a list into a function.Each item in the list, consists of a start date, end date, int and symbol.q)requests:((2021.06.07;2021.06.09;53696;`Sent);(2021.06.12;2021.06.14;81840;`Sent))I then have a function that creates a...

Convert Tree into Table columns

Hi All,I have a problem statement where I need to convert Tree kind of rows into columns. For Ex:-I have a table Tree where I have rows as follows :Rule | Key | ValueRule1 | Key1 | Val1Rule1 | Key2 | Val2Rule2 | Key1 | Val3Rule2 | Key2 | Val4Rule3 | ...

KDB_Dev by New Contributor
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Important ML Toolkit Changes

For anyone that uses the KX Machine Learning repos (Toolkit/AutoML/NLP) the following is relevant. Added to this group as the implications of the change may be seen anywhere these repos or select functionality is used extensively.Today we released an...

cmccarthy1 by New Contributor II
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Minimum Requirements To Achieve Streaming In KX Dashboards

Have sort of asked this before, but had to drop to complete other projects-- but we're back...So, I'm trying to achieve streaming data within Dashboards. I've gone through the docs (PDFs) and tutorials (videos etc) and still can't seem to achieve suc...

planefan by New Contributor III
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ODBC-native-escape clause

Hi,In Simba ODBC driver documention says:"In the Edit Custom SQL dialog box, write a SQL statement that includes an ODBC-native-escape clause containing your q query. For more information, see "Native Syntax" in the ODBC 4.0 Specification"Could some ...

Joining tables with lists of data

Hi All, wondering if someone can help.I have 3 tables with a column of lists. I want to take the the tables and add them to the first tables list.So for examplea:([key1:`a`b`c]val:(enlist 1;enlist 2;enlist 3))b:([key1:`a`b`c]val:(enlist 4;enlist 5;en...

WindowJoin

I have a table full of trades, and a table full of quote updates. My goal is to use a windowjoin to get aggregate figures -- however I have an extra parameter that I need to pay attention too (usually coming from the trades table). Thus, I've been us...

planefan by New Contributor III
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Q for examples - Simple Structural transforms

Good Morning!Due to a lot of work at the beginning of the year, I had to slow down the study pace.I am currently at:https://code.kx.com/q/learn/q-by-examples/Topic: Structural transformsI was able to understand all the examples, except:q) 0 3 _ /: 2 ...

How this line works

Can someone explain me how the following line works line works:p: raze(,'/)' [rs] Here the rs is N * N dimensional list and each cell inside it is a M * M size string list (i.e each cell is a list of M strings of length M)Output p is NM * NM dimensio...

Timeout on a sync call

How do I put a timeout on the following sync call ?h:hopen `:192.168.12.15:5001@[h;`func;{0N!x}]The other approach is doing an async call and putting a timeout on the callback. This is something I am not looking for.Thanks.

Visual Inspector chart question - Kx Developer 1.3.1

Hi,Is it me, or there's really no way to chart a typical market data timeseries without the inherent date/time gaps along the X-axis? A 1-minute data table (with no data from 4PM to 9:30AM), as per below:yields the following line chart:I don't see a ...

JP by New Contributor III
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Dynamic Timeframe List In WindowJoin

Happy New Year Everyone, I'm hoping to set the timeframe for my windowjoin to start at 9:30 instead of time - interval:w: (0;0)+\:table `timestamp;As is above, it will give me a start/end time of the timestamp. I'm hoping to make it so that the start...

planefan by New Contributor III
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