Monthly Archives: February 2019

Sorting a NumPy Array of Arrays

Posted on February 27, 2019 by jamesdmccaffrey

I was working on a Python program recently and I needed to sort a NumPy array-of-arrays based on one of the columns. For example, if the data is: [[10. 13. 15.] [19. 11. 14.] [15. 17. 12.] [14. 12. 18.]] … Continue reading →

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I Give a Talk About Anomaly Detection Using Neural Clustering with PyTorch

Posted on February 26, 2019 by jamesdmccaffrey

About once a week, I give a short (typically 45 minutes long) talk at the large tech company I work for. I recently gave a talk about . . well, it’s not so easy to explain. Let me try. Anomaly … Continue reading →

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Generating Normal / Gaussian Distributed Random Values Using JavaScript

Posted on February 25, 2019 by jamesdmccaffrey

I’ve been working with JavaScript recently. Just for fun, I thought I’d tackle the problem of generating Gaussian distributed (aka Normal, aka bell-shaped) pseudo-random values, using raw JavaScript. There are several algorithms to do this but I prefer a simplified … Continue reading →

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Rank Order Accuracy using Discounted Cumulative Gain

Posted on February 22, 2019 by jamesdmccaffrey

Suppose you have some system that predicts the ordering (ranking) of items and you want to compute a measure of prediction accuracy. It’s a bit of a tricky problem. One approach is to use what’s called Discounted Cumulative Gain (DCG). … Continue reading →

Posted in Miscellaneous | 3 Comments

My Top Ten Favorite Yeti Movies

Posted on February 21, 2019 by jamesdmccaffrey

I live in the Pacific Northwest. We’ve had quite a bit of snow this winter but luckily no yetis. I’d always assumed that there are dozens of movies about yeti aka the abominable snowman. Well, there are lots of movies … Continue reading →

Posted in Top Ten | 4 Comments

Unraveling the Mysteries of a PyTorch LSTM Module

Posted on February 20, 2019 by jamesdmccaffrey

Update: See https://jamesmccaffreyblog.com/2019/06/28/the-pytorch-lstm-module-input-shape-tricked-me-again/ Because PyTorch is so new, there aren’t many code examples to be found on the Internet, and the documentation is frequently out-of-sync with the latest code. I’ve worked with very new, rapidly changing code libraries before and … Continue reading →

Posted in Machine Learning, PyTorch | 1 Comment

Neural Network Activation Functions with JavaScript

Posted on February 19, 2019 by jamesdmccaffrey

I’ve been exploring the idea of implementing neural networks using raw JavaScript. None of the individual parts of a neural network (weights and biases, initialization, input-output, etc.) are hugely complicated by themselves, but there are a lot of parts. One … Continue reading →

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Recap of the 2019 TDWI Conference

Posted on February 18, 2019 by jamesdmccaffrey

I spoke at the 2019 TDWI Conference. The event ran from February 10-15 and was in Las Vegas. I estimate there were about 500 people at the conference. Like most technical conferences, there were standard speaking sessions, workshops and training … Continue reading →

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Quick and Easy Naive Bayes Classification

Posted on February 14, 2019 by jamesdmccaffrey

Somewhat unusually, I can get a lot of technical work done while I travel. When I’m sitting in a terminal or sitting on a plane, there are no distractions and I do what I call mental coding. On a recent … Continue reading →

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Reading a Text File of Numbers into a JavaScript Matrix Using Node.js

Posted on February 12, 2019 by jamesdmccaffrey

I’ve been looking at the idea of creating a neural network using plain JavaScript running in the Node.js system. A basic utility task is to read a text file of training data into memory as a numeric matrix. For my … Continue reading →

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