Eclipse Deeplearning4j is the first commercial-grade, open-source, distributed deep-learning library written for Java and Scala. Integrated with Hadoop and Apache Spark, DL4J brings AI to business environments for use on distributed GPUs and CPUs.

Distributed

DL4J takes advantage of the latest distributed computing frameworks including Apache Spark and Hadoop to accelerate training. On multi-GPUs, it is equal to Caffe in performance.

Open Source

The libraries are completely open-source, Apache 2.0, and maintained by the developer community and Konduit team.

JVM/Python/C++

Deeplearning4j is written in Java and is compatible with any JVM language, such as Scala, Clojure or Kotlin. The underlying computations are written in C, C++ and Cuda. Keras will serve as the Python API.

What's included?

Deep neural nets are capable of record-breaking accuracy. For a quick neural net introduction, please visit our overview page. In a nutshell, Deeplearning4j lets you compose deep neural nets from various shallow nets, each of which form a so-called `layer`. This flexibility lets you combine variational autoencoders, sequence-to-sequence autoencoders, convolutional nets or recurrent nets as needed in a distributed, production-grade framework that works with Spark and Hadoop on top of distributed CPUs or GPUs.

There are a lot of parameters to adjust when you're training a deep-learning network. We've done our best to explain them, so that Deeplearning4j can serve as a DIY tool for Java, Scala, Clojure and Kotlin programmers.

While Deeplearning4j is written in Java, the Java Virtual Machine (JVM) lets you import and share code in other JVM languages. These tutorials are written in Scala, the de facto standard for data science in the Java environment. There’s nothing stopping you from using any other interpreter such as Java, Kotlin, or Clojure.

If you’re coming from non-JVM languages like Python or R, you may want to read about how the JVM works before using these tutorials. Knowing the basic terms such as classpath, virtual machine, “strongly-typed” languages, and functional programming will help you debug, as well as expand on the knowledge you gain here. If you don’t know Scala and want to learn it, Coursera has a great course named Functional Programming Principles in Scala.

Tutorials covering basic DL4J features

End to End Tutorials showing specific solutions

With deep learning, we can compose a deep neural network to suit the input data and its features. The goal is to train the network on the data to make predictions, and those predictions are tied to the outcomes that you care about; i.e. is this transaction fraudulent or not, or which object is contained in the photo? There are different techniques to configure a neural network, and all of them build a relational hierarchy between the inputs and outputs.

In this tutorial, we are going to configure the simplest neural network and that is logistic regression model network.

Regression is a process that helps show the relations between the independent variables (inputs) and the dependent variables (outputs). Logistic regression is one in which the dependent variable is categorical rather than continuous - meaning that it can predict only a limited number of classes or categories, like a switch you flip on or off. For example, it can predict that an image contains a cat or a dog, or it can classify input in ten buckets with the integers 0 through 9.

A simple logistic regression calculates x*w + b = y. Where x is an instance of input data, w is the weight or coefficient that transforms that input, b is the bias and y is the output, or prediction about the data. The biological terms show how this artificial neuron loosely maps to a neuron in the human brain. The most important point is how data flows through and is transformed by this structure.

What will we learn in this tutorial?

We’re going to configure the simplest network, with just one input layer and one output layer, to show how logistic regression works.

Imports

Configuring logistic regression layers

We are going to first build the layers and then feed these layers into the network configuration.

Why we didn’t build an input layer

You may be wondering why didn’t we write any code for building our input layer. The input layer is only a set of inputs values fed into the network. It doesn’t perform a calculation. It’s just an input sequence (raw or pre-processed data) coming into the network, data to be trained on or to be evaluated. Later, we are going to work with data iterators, which feed input to a network in a specific pattern, and which can be thought of as an input layer of the network.