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Category: Machine Learning

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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Using Azure ML To Approve Expenses Automatically

Published 2018-11-27 by Kevin Feasel

Isabelle Van Campenhoudt walks us through a scenario of using Azure ML to find expense reports which should automatically be approved, reducing the workload for approvers:

My partner in crime Serge Luca aka Doctor Flow is the author of a nice and complex expenses approval system in Microsoft Flow .
One year ago, he asked me to add analytics to his Flow.  This year he has the interesting idea to add a machine-learning based approval in his flow and suggest me to work on it. The idea is the following: Since we have a lot of approvals in our system, can a machine learn and found some decision pattern to apply automatically to each expenses request ?
I decided to use the Microsoft Azure Machine Learning Studio. In this tool you can build experiments and use some of the most common and useful machine learning algorithms. It was amazing to see how easy it is to create and consume machine learning .

This contrasts with Ginger Grant’s nightmare scenario pretty well:  instead of trying to get the ML process to do all of the work, create a process which takes care of the really easy stuff and leave harder tasks to specialists with a deeper understanding of the rules.  That way they don’t have to spend their time on trivialities.

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No Laptop For You: A Case Of Machine Learning Failure

Published 2018-11-26 by Kevin Feasel

Ginger Grant walks us through a scenario where Lenovo refused to sell her a laptop four times:

Buying a laptop from Lenovo reminded me of an episode of Seinfeld when Elaine was trying to buy soup.  For some unknown reason, when I placed an order on their website and gave them my money, Lenovo gave me a Cancellation Notice, the email equivalent of “No Soup for you!”  After placing an order, about 15 minutes later, I received a cancellation notice.  I called customer service.  They looked at the order and advised me the systemincorrectly cancelled the order.  I was told to place the order again as they had resolved the problem.  I created a new order, and just like the last time, I received the No Laptop for You cancellation email.  I called back. This time I was told that the system thinks I am a fraud. Now I have no laptop and I have been insulted.

In all the talk of ML running the future, one thing that gets forgotten is that models, being simplifications of reality, necessarily make mistakes.  Failing to have some sort of manual override means, in this case, throwing away money for no good reason.

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A Pessimistic View Of The State Of Deep Learning

Published 2018-11-20 by Kevin Feasel

William Vorhies provides us a negative (and necessary) look at the current state of Deep Learning solutions:

Reinforcement Learning (RL) is arguably the hottest research area in AI today because it appears RL can be adapted to any problem that has a well-defined reward function.  That encompasses game play, robotics, self-driving cars, and frankly pretty much else in machine learning.

Within RL, the hottest research area is Deep RL which means using a deep neural net as the ‘agent’ in the training.  Deep RL is seen as the form of RL with the most potential to generalize over the largest number of cases and perhaps the closest we’ve yet come to AGI (artificial general intelligence).

Importantly, Deep RL is also the technique used to win at Alpha Go which brought it huge attention.

The problem is, according to Alex Irpan, a researcher on the Google Brain Robotics team that about 70% of the time they just don’t work.

Alex has written a very comprehensive article critiquing the current state of Deep RL, the field with which he engages on a day-to-day basis.  He lays out a whole series of problems and we’ve elected to focus on the three that most clearly illustrate the current state of the problem with notes from his work.

Vorhies is not unduly negative and is optimistic in the medium to long term, but he is right in noting that there is a lot of work yet to do in this field.

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Object Detection Methods In Convolutional Neural Networks

Published 2018-11-20 by Kevin Feasel

Xindian Long explains some of the techniques which convolutional neural networks use to discern objects in images:

Can we do object detection in a smart way by only looking at some of the windows? The answer is yes. There are two approaches to find this subset of windows, which lead to two different categories of object detection algorithms.

  1. The first algorithm category is to do region proposal first. This means regions highly likely to contain an object are selected either with traditional computer vision techniques (like selective search), or by using a deep learning-based region proposal network (RPN). Once you have gathered the small set of candidate windows, you can formulate a set number of regression models and classification models to solve the object detection problem. This category includes algorithms like Faster R-CNN[1], R_FCN[2] and FPN-FRCN[3]. Algorithms in this category are usually called two-stage methods. They are generally more accurate, but slower than the single-stage method we introduce below.
  2. The second algorithm category only looks for objects at fixed locations with fixed sizes. These locations and sizes are strategically selected so that most scenarios are covered. These algorithms usually separate the original images into fixed size grid regions. For each region, these algorithms try to predict a fixed number of objects of certain, pre-determined shapes and sizes. Algorithms belonging to this category are called single-stage methods. Examples of such methods include YOLO[4], SSD[5] and RetinaNet[6]. Algorithms in this category usually run faster but are less accurate. This type of algorithm is often utilized for applications requiring real-time detection.

We’ll discuss two common object detection methods below in more detail.

This is a high-level explanation with no code, but it does a good job of describing at that level what is going on.

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Running Python-Based ML Tasks In Excel

Published 2018-11-19 by Kevin Feasel

Tony Roberts shows off some of the functionality of PyXLL:

Once we’ve done the hard work of building and testing a model we need to put it to some use! Excel is a great front-end tool for playing with data interactively. It’s used virtually everywhere and so being able to deliver your model in Excel to non-developer users massively opens up opportunities for how it can be used in your business. Even if the model is being used as part of a real-time or batch system, being able to call the model interactively can be really helpful when trying to understand the behaviour of a system.

Fortunately now the model is written in Python getting it into Excel is extremely simple. PyXLL, the Python Excel Add-In has everything we need to write Python for Excel. All we need to do is add a few @xl_func decorators from the pyxll module and configure the PyXLL add-in to load the module containing our model.

If you’re not already familiar with PyXLL, check out the introduction to PyXLL from the user guide.

I mean, if the data’s going to live in Excel spreadsheets anyhow…

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Explaining Neural Networks With H2O

Published 2018-11-07 by Kevin Feasel

Shirin Glander explains some of the concepts behind neural networks using H2O as a guide:

Before, when describing the simple perceptron, I said that a result is calculated in a neuron, e.g. by summing up all the incoming data multiplied by weights. However, this has one big disadvantage: such an approach would only enable our neural net to learn linearrelationships between data. In order to be able to learn (you can also say approximate) any mathematical problem – no matter how complex – we use activation functions. Activation functions normalize the output of a neuron, e.g. to values between -1 and 1, (Tanh), 0 and 1 (Sigmoid) or by setting negative values to 0 (Rectified Linear Units, ReLU). In H2O we can choose between Tanh, Tanh with Dropout, Rectifier (default), Rectifier with Dropout, Maxout and Maxout with Dropout. Let’s choose Rectifier with Dropout. Dropout is used to improve the generalizability of neural nets by randomly setting a given proportion of nodes to 0. The dropout rate in H2O is specified with two arguments: hidden_dropout_ratios, which per default sets 50% of hidden (more on that in a minute) nodes to 0. Here, I want to reduce that proportion to 20% but let’s talk about hidden layers and hidden nodes first. In addition to hidden dropout, H2O let’s us specify a dropout for the input layer with input_dropout_ratio. This argument is deactivated by default and this is how we will leave it.

Read the whole thing and, if you understand German, check out the video as well.

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Azure ML Studio Supports R 3.4

Published 2018-11-02 by Kevin Feasel

David Smith notes that Azure ML Studio now supports R version 3.4:

With the Execute R Script module you can immediately use more than 650 R packages which come preinstalled in the Azure ML Studio environment. You can also use other R packages (including packages not on CRAN) and source in R scripts you develop elsewhere (as shown above), although this does require the time to install them in the Studio environment. You can even create custom ML Studio models encapsulating R code for others to use in the drag-and-drop environment.

If you’re new to Azure ML Studio, check out the Quickstart Tutorial for R to learn how use the Execute R Script module, and to check out what’s new in the latest update follow the link below.

Click through for more details.

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Comparing TensorFlow Versus PyTorch

Published 2018-10-19 by Kevin Feasel

Anirudh Rao compares PyTorch to TensorFlow:

For small-scale server-side deployments both frameworks are easy to wrap in e.g. a Flask web server.

For mobile and embedded deployments, TensorFlow works really well. This is more than what can be said of most other deep learning frameworks including PyTorch.

Deploying to Android or iOS does require a non-trivial amount of work in TensorFlow.

You don’t have to rewrite the entire inference portion of your model in Java or C++.

Other than performance, one of the noticeable features of TensorFlow Serving is that models can be hot-swapped easily without bringing the service down.

Read on for the full comparison.

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