Brian Rhee

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A Beginner's Guide To Understanding Convolutional Neural Networks Part 2

<b>Introduction</b><p>In this post, we’ll go into a lot more of the specifics of ConvNets. <b>Disclaimer:</b> Now, I do realize that some of these topics are quite …

Deep Learning

CS231n Convolutional Neural Networks for Visual Recognition

Table of Contents:<p>Convolutional Neural Networks (CNNs / ConvNets)<p>Convolutional Neural Networks are very similar to ordinary Neural Networks from the …

Deep Learning

AQR: Investor Worries Over Trading Costs May Be Overblown

The total costs of equity trading just went down.<p>In a new paper, AQR principals Andrea Frazzini, Ronen Israel, and Tobias Moskowitz argue that equity …

Clever trick with exec

Shame on me that I didn’t know how clever the following syntax is<p>exec a!b from tab <br>It is quite possible that to achieve the same effect I have used …

Difference between 'exec' and 'select'; prime factorization algorithm

First, I can't understand the difference between exec and select in kdb. The reference for exec doesn't really help much!<p>Second, I'm trying to write …

How to remove element from list in KDB?

For instance, I have:<p>and I want to remove the (). I have tried using ? (match)<p>but that just gives ().<p>What is the correct expression?<p><b>Background</b><p>I often …

Functional Select Kdb Queries

Functional queries allow specifying column names as symbols to typical q-sql select/exec/delete columns, this is extremely useful when you want to …

Databases

Knowledge Base/Databases/Kdb

From Thalesians<p>Jump to: navigation, search<p>Acknowledgements<p><i>We would like to thank Ed Bierly, Jeff Borror, Mahesh BP, Bernard Cena, Aaron Davies, Ben</i> …

How do I use the functional form of . (dot) apply? - kdbfaq

Short answer:<p>(Note that there is another overload for . with three arguments, called protected execution, which is invoked when the first argument to …

Data Science

How do I split a list?

If you want to split the list into lists of equal size, see this related faq on the # (take) operator.<p>If you want to split a string on a delimiter, …

Productivity

q Query: creating grid from a table

I have written a function that wraps a q query that returns me a table with three columns - c1,c2 and vals. How do I create a grid (2D array) such …

Design

How does fby work?

According to code.kx.com, fby is short for filter-by, and it is commonly used as the q equivalent to SQL’s HAVING clause (though, like where, fby is …

Databases

QforMortals/primitive operations - Kx Wiki

From Kx Wiki<p>Jump to: navigation, search<p>Primitive Operations<p>Introduction to Functions<p>Function Notation<p>Operators and functions are closely related. In …

Programming

DotQ/DotQDotfu - Kx Wiki

From Kx Wiki<p>Jump to: navigation, search<p>.Q.fu<p>Another performance improvement is one I'm proud of because I discovered the need for it (and Steve Apter …

kdb+/q: Check if argument has been supplied to the function call

Say we have function fun with two arguments, second one is optional. How to check within the function whether the second, optional argument has been …

Behavior

Operators Archives

Short answer: It takes a function of N operands and creates a new function that applies the original to each set of corresponding elements from N …

Archives

q easter egg?

If you try to run 9 vs til 81, you will get two lists each with 81 values. And now try to invoke this with values other than 9 and 81 :)<p>It seems that …

My experiments while learning q KDB +

I implemented the msum verb in kdb+ using the sliding window code.<p>First step is to find the sliding window function in q using scan operator …

Python Programming

Symbols, Enumerations and strings in kdb

In this tutorial we will explain what symbols are and how we can enumerate symbols to enforce values to conform. By fully understanding what symbols …

Wall Street

QforMortals2/functions - Kx Wiki

From Kx Wiki<p>Jump to: navigation, search<p>Functions<p>Overview<p>In this chapter, we cover functions in depth. Before starting, you may wish to review the …

Databases

kdb+/q - Concatenating columns

This post shows how you can concatenate values in two or more columns of a table in kdb, into a single value. Consider the following table:In SQL, …

When does : (amend) not modify its first argument?

Short answer: When 1) projected or 2) modified by an adverb, e.g., :/: :\: or :’<p>Normally, the : (amend) function is used to assign a value to a …

What are 0!, 1! and 2!?

When !’s left argument is a positive integer, it sets the key fields of a table:<p>q)flip `a`b`c ! (1 2 3; 1 2 3; 1 2 3)<br>a b c<br>—–<br>1 1 1<br>2 2 2<br>3 3 3<br>q)1! flip …

Extreme Sports

online book - kdb+/q faq - Kdb+ is the registered trademark of Kx Systems, Inc.

According to code.kx.com, fby is short for filter-by, and it is commonly used as the q equivalent to SQL’s HAVING clause (though, like where, fby is …

Databases

You searched for untyped list

If you are defining the list’s contents at the same time you declare it, this is easy:<p>q)list: (`sector; 47)<br>q)type list<br>0h<br>q)list ,: …

Time Management

How do I store mixed data types in a single column of a table? - kdbfaq

The first time we needed a column that can hold values of multiple types, we tried something similar to the following:<p>q)t: ([] thing: ())<br>q)meta t<br>c | …

Select value from mixed-type row in KDB

We defined our KDB table with the type C (i.e. Character array). First value which we inserted had a type String, second value had a type int (i.e. …

string functions? like search replace regex? - TimeStored

When selecting based on the condition of a string or char array column, <b>“like”</b> is normally used.<p>The verb like takes two arguments<br>1. The list of …