Streaming data from Raspberry Pi to Oracle NoSQL via Node-RED

Christos - Iraklis Tsatsoulis Internet of Things, Node-RED, Oracle NoSQL, Raspberry Pi 0 Comments

Starting from version 4.2, Oracle NoSQL now offers drivers for Node.js and Python, in addition to the existing ones for Java, C, and C++; this is good news for data science people, like myself, since we are normally not accustomed to code in Java or C/C++. So, I thought to build a short demo project, putting into test both the …

Workaround for disclosed af:query issue on ADF 12.2.1

Michael Koniotakis Oracle ADF 0 Comments

While migrating ADF applications from 11 to 12 we stepped on a known bug in ADF 12.2.1 Bug 22469635 : AF:QUERY COMPONENT BUTTONS DON’T WORK WHEN “DISCLOSED” SET TO “FALSE” Since this is not resolved yet we needed a workaround. There were search criteria with disclosed=”false” in pages with rich layout that the user should expand it only if he …

sparklyr: a test drive on YARN

Christos - Iraklis Tsatsoulis R, Spark 2 Comments

sparklyr is a new R front-end for Apache Spark, developed by the good people at RStudio. It offers much more functionality compared to the existing SparkR interface by Databricks, allowing both dplyr-based data transformations, as well as access to the machine learning libraries of both Spark and H2O Sparkling Water. Moreover, the latest RStudio IDE v1.0 now offers native support …

Nonlinear regression using Spark – Part 2: sum-of-squares objective functions

Constantinos Voglis Data Science, Spark 4 Comments

This post is the second one in a series that discusses algorithmic and implementation issues about nonlinear regression using Spark. In the previous post we identified a small window for contribution into Spark MLlib by adding methods for nonlinear regression, starting with the definition and implementation of a general nonlinear model. We remind the reader that regression is essentially an …

Classification in Spark 2.0: “Input validation failed” and other wondrous tales

Christos - Iraklis Tsatsoulis Data Science, Spark 4 Comments

Spark 2.0 has been released since last July but, despite the numerous improvements and new features, several annoyances still remain and can cause headaches, especially in the Spark machine learning APIs. Today we’ll have a look at some of them, inspired by a recent answer of mine in a Stack Overflow question (the question was about Spark 1.6 but, as …

How to evaluate R models in Azure Machine Learning Studio

Constantinos Voglis Azure Machine Learning Studio, Data Science, R 5 Comments

Azure Machine Learning Studio is a GUI-based integrated development environment for constructing and operationalizing machine learning workflows. The basic computational unit of an Azure ML Studio workflow (or Experiment) is a module which implements machine learning algorithms, data conversion and transformation functions etc. Modules can be connected by data flows, thus implementing a machine learning pipeline. A typical pipeline in …

Installing the additional R packages in Oracle Big Data Lite VM 4.5.0

Christos - Iraklis Tsatsoulis R 2 Comments

Oracle has just released version 4.5.0 of the Big Data Lite VM which, when it comes to R, still suffers from the issues we had pinpointed for the previous version 4.4.0 (and then some). The first attempt to install the additional packages fails with a ‘cannot open URL’ error: Fortunately, the warning about the proxy helps to locate the issue, …

ViewCriteria issue when using more than once attribute with LOV based on switcher (Oracle JDeveloper 12.2.1.0)

Rigas Papazisis Fusion Middleware, Oracle ADF 2 Comments

Almost a year ago I wrote this post about a ViewCriteria issue when using the same attribute twice in Oracle JDeveloper 12.1.3.0. Now I came across another issue with ViewCriteria, in Oracle JDeveloper 12.2.1.0 this time, again related with a multiple insertion of an attribute but with a more complex scenario this time. Consider having an attribute with applied LOV that …

Manifest entry Weblogic-Application-Version causes log messages not to be shown on EM 12.2.1

Rigas Papazisis Fusion Middleware, Oracle ADF, WebLogic 0 Comments

Recently we migrated an ADF app from 12.1.3 to 12.2.1 and we faced a problem with the log messages in the application server. Specifically, the deployed application returned zero log messages when navigating to em>application>Logs>view Log messages. The log configuration and the search results are as you can see in the following screenshots:   After many checks and dummy applications …