Category: Machine Learning

Genetic Algorithms In R

Published 2019-01-24 by Kevin Feasel

Pablo Casas touches on one of my favorite lost causes:

In machine learning, one of the uses of genetic algorithms is to pick up the right number of variables in order to create a predictive model.
To pick up the right subset of variables is a problem of combinatory logic and optimization.
The advantage of this technique over others is that it allows the best solution to emerge from the best of the prior solutions. An evolutionary algorithm which improves the selection over time.
The idea of GA is to combine the different solutions generation after generation to extract the best genes (variables) from each one. That way it creates new and more fit individuals.
We can find other uses of GA such as hyper-tunning parameters, finding the maximum (or minimum) of a function, or searching for the correct neural network architecture (neuroevolution), among others.

I’ve seen a few people use genetic algorithms in the past decade, but usually for hyperparameter tuning rather than as a primary algorithm. It was always the “algorithm of last resort” even before neural networks took over the industry, but if you want to spend way too much time on the topic, I have a series. If you have too much time on your hands and meet me in person, ask about my thesis.

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Adding ML Services On Windows Server Core

Published 2019-01-23 by Kevin Feasel

Kevin Chant shows us how to add SQL Server ML Services to an already-existing SQL Server installation on Windows Server Core:

It’s important to try and use an install set that is the same level of Service pack as your current install. Otherwise, you could end up installing multiple patches to get the SQL Launchpad service to work. Which is something discussed in a previous post here.
I know some companies have a central installer for SQL Server and then have all the updates in another location. Hence, if you are in such an environment be prepared to run multiple updates from that location after the install.

This is definitely one of the features which is easier to install from the beginning than to install after the fact.

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An Explanation Of Convolutional Neural Networks

Published 2019-01-18 by Kevin Feasel

Shirin Glander explains some of the mechanics behind Convolutional Neural Networks:

Convolutional Neural Nets are usually abbreviated either CNNs or ConvNets. They are a specific type of neural network that has very particular differences compared to MLPs. Basically, you can think of CNNs as working similarly to the receptive fields of photoreceptors in the human eye. Receptive fields in our eyes are small connected areas on the retina where groups of many photo-receptors stimulate much fewer ganglion cells. Thus, each ganglion cell can be stimulated by a large number of receptors, so that a complex input is condensed into a compressed output before it is further processed in the brain.

If you’re interested in understanding why a CNN will classify the way it does, chapter 5 of Deep Learning with R is a great reference.

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Where Machine Learning And Econometrics Collide

Published 2019-01-16 by Kevin Feasel

Dave Giles shares some thoughts on how machine learning and econometrics relate:

What is Machine Learning (ML), and how does it differ from Statistics (and hence, implicitly, from Econometrics)?

Those are big questions, but I think that they’re ones that econometricians should be thinking about. And if I were starting out in Econometrics today, I’d take a long, hard look at what’s going on in ML.

Click through for some quick thoughts and several resources on the topic.

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Auto ML With SQL Server 2019 Big Data Clusters

Published 2019-01-16 by Kevin Feasel

Marco Inchiosa has a model scenario for using Big Data Clusters to scale out a machine learning problem:

H2O provides popular open source software for data science and machine learning on big data, including Apache Spark^TM integration. It provides two open source python AutoML classes: h2o.automl.H2OAutoML and pysparkling.ml.H2OAutoML. Both APIs use the same underlying algorithm implementations, however, the latter follows the conventions of Apache Spark’s MLlib library and allows you to build machine learning pipelines that include MLlib transformers. We will focus on the latter API in this post.
H2OAutoML supports classification and regression. The ML models built and tuned by H2OAutoML include Random Forests, Gradient Boosting Machines, Deep Neural Nets, Generalized Linear Models, and Stacked Ensembles.

The post only has a few lines of code but there are a lot of working parts under the surface.

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Practical AI Workshop Notebooks

Published 2019-01-04 by Kevin Feasel

David Smith has published a set of notebooks from the Practical AI for the Working Software Engineer workshop:

Last month, I delivered the one-day workshop Practical AI for the Working Software Engineer at the Artificial Intelligence Live conference in Orlando. As the title suggests, the workshop was aimed at developers, bu I didn’t assume any particular programming language background. In addition to the lecture slides, the workshop was delivered as a series of Jupyter notebooks. I ran them using Azure Notebooks (which meant the participants had nothing to install and very little to set up), but you can run them in any Jupyter environment you like, as long as it has access to R and Python. You can download the notebooks and slides from this Github repository (and feedback is welcome there, too).

Read on for details about those notebooks and to get your own copies.

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MLflow 0.8.1 Released

Published 2018-12-31 by Kevin Feasel

Aaron Davidson, et al, announce a new version of Databricks MLflow:

When scoring Python models as Apache Spark UDFs, users can now filter UDF outputs by selecting from an expanded set of result types. For example, specifying a result type of pyspark.sql.types.DoubleType filters the UDF output and returns the first column that contains double precision scalar values. Specifying a result type of pyspark.sql.types.ArrayType(DoubleType) returns all columns that contain double precision scalar values. The example code below demonstrates result type selection using the result_type parameter. And the short example notebook illustrates Spark Model logged and then loaded as a Spark UDF.

Read on for a pretty long list of updates.

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Analyzing Customer Churn With Keras And H2O

Published 2018-12-13 by Kevin Feasel

Shirin Glander has released code pertaining to a forthcoming book chapter:

This is code that accompanies a book chapter on customer churn that I have written for the German dpunkt Verlag. The book is in German and will probably appear in February: https://www.dpunkt.de/buecher/13208/9783864906107-data-science.html.
The code you find below can be used to recreate all figures and analyses from this book chapter. Because the content is exclusively for the book, my descriptions around the code had to be minimal. But I’m sure, you can get the gist, even without the book. 😉

Click through for the code. This is using the venerable AT&T customer churn data set.

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Working With Images In Spark 2.4

Published 2018-12-11 by Kevin Feasel

Tomas Nykodym and Weichen Xu give us an update on working with images in the most recent version of Apache Spark:

An image data source addresses many of these problems by providing the standard representation you can code against and abstracts from the details of a particular image representation.
Apache Spark 2.3 provided the ImageSchema.readImages API (see Microsoft’s post Image Data Support in Apache Spark), which was originally developed in the MMLSpark library. In Apache Spark 2.4, it’s much easier to use because it is now a built-in data source. Using the image data source, you can load images from directories and get a DataFrame with a single image column.
This blog post describes what an image data source is and demonstrates its use in Deep Learning Pipelines on the Databricks Unified Analytics Platform.

If you’re interested in working with convolutional neural networks or otherwise need to analyze image data, check it out.

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Building A Convolutional Neural Network With TensorFlow

Published 2018-11-27 by Kevin Feasel

Anirudh Rao walks us through Convolutional Neural Networks in TensorFlow:

What Are Convolutional Neural Networks?

Convolutional Neural Networks, like neural networks, are made up of neurons with learnable weights and biases. Each neuron receives several inputs, takes a weighted sum over them, pass it through an activation function and responds with an output.

The whole network has a loss function and all the tips and tricks that we developed for neural networks still apply on Convolutional Neural Networks.

Pretty straightforward, right?

Neural networks, as its name suggests, is a machine learning technique which is modeled after the brain structure. It comprises of a network of learning units called neurons.

These neurons learn how to convert input signals (e.g. picture of a cat) into corresponding output signals (e.g. the label “cat”), forming the basis of automated recognition.

Let’s take the example of automatic image recognition. The process of determining whether a picture contains a cat involves an activation function. If the picture resembles prior cat images the neurons have seen before, the label “cat” would be activated.

Hence, the more labeled images the neurons are exposed to, the better it learns how to recognize other unlabelled images. We call this the process of training neurons.

I (finally) finished chapter 5 of Deep Learning in R, which is all about CNNs. It’s interesting just how open CNNs are for post hoc understanding, totally at odds with the classic neural network reputation for being a black box full of dark magic.

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