olpa, OSS developer

An disappointment after getting EEG-SMT working: the resulting measurement is just a noice. It is a challenging task for a beginner to understand what is going wrong.

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There is a number of software intended for EEG works. The EEG-SMT quick start guide suggests Electric Guru, BrainBay and OpenVibe, but it implies the use of a legacy operating system instead of Linux.

This post extends the quick start to have Linux notes. The content:

* Install OpenVIBE
* Connect STM-EEG to Linux
* Configure OpenVIBE
* Get the signal

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My old interest is to influece the brain to make it working more efficient.

One of the approaches is to learn complete relaxation, or in other word meditation. The book “Meditation für Skeptiker” by Ulrich Ott suggests a scientific evidence for this claim, and I decided to try.

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Writing a DWD+RW under Linux should be simple, something like:

$ wodim speed=2 dev=/dev/sr0 -v -data ubuntu-16.04.3-desktop-i386.iso

However, in my case it fails. Some background knowledge suggests to format the disc first, but blanking the disc fails too.

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There is a task, which can’t be avoided when developing serverless applicatoins on Amazon Web Services:

How to return a custom status code from a REST API?

One of the approaches is to use “prefix mapping”, like for example is shown in this amazon blog post: Error Handling Patterns in Amazon API Gateway and AWS Lambda by Bryan Liston.

The only problem is that the approach doesn’t always work. After a long debuggin session with many false tries, I’ve found the reason.

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Here are a few links which helped me to understand what to use to mock microservices with REST API. Just for a case, I’ve choosen wiremock because I need Java and saboteur functionality.

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Selenium is a web browser automation software. In Ubuntu 16.04 it doesn’t work out of the box, and external components should be installed. In this post I note how to install them locally without affecting the system.

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I’ve seriously tried TDD in a real project, writing tests before code and following the red-green-refactor cycle. Short summary:

* I believe in TDD now;
* training and practice are required to learn TDD, reading books is not enough;
* the initial time investment is big.

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Rviz A 3d visualization environment for robots. Sounds intriguing and useful, but the first steps in it are painful. In particular, moving anything is surprisingly a very hard task for a novice who doesn’t know about the right way. Now I have enough experience to describe what to do: Moving things in rviz.

The Linux command line and other software based on readline library support vi editing mode. After I worked on a new system with the default settings for a while, I noticed that I miss this mode very much.

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Based on the article How to Run Your Own Git Server, I’ve constructed a small list for fast git setup for temporary projects.

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I was a speaker at the TeX users meeting in Wuppertal, with the talk “Erfahrung und Vorhersagen für automatisches XML-nach-PDF-Publizieren mit TeX” (experience and prediction for automatical from-XML-to-PDF publishing using TeX).

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python libxml2 dita

For correct transformation of DITA files (XML-standard for modular documentation), it is necessary to pull information from DTD (document type definition). In my python code, sometimes I did get this information and sometimes not. Now I’ve tracked the source of instability and corrected the code.

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The PDF is of some non-standard landscape layout, the printer is an usual A4 printer, the software can’t handle the mix correctly. The solution is to tune the dimensions of the PDF pages manually.

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For XML to DocBook to .docx conversion, I found that “le-tex transpect” framework has solved many technical issues already, so I overcame the “not invented here syndrome” and decided to rely on this tool. To tune the stylesheets for own needs, I created a github copy of the repository: docxtools. To run the stylesheets outside the framework, a special setup is required. The setup is described in the folder “doc/hello-world“.

In theory, changing content of an Excel file is easy:

* Parse XML from the zip-file
* Change XML
* Save XML into the zip

In practice I got the error: >>Von Excel wurde unlesbares Inhalt in … gefunden. Möchten Sie den Inhalt dieser Arbeitsmappe wiederherstellen?< < (English: "Excel found unreadable content...") Read the rest of this entry »

In the year 2001 I started to experiment with GUI applications in Python. The experience was summarized and published in the article “A complete Python Tkinter sample application for a long operation“. Now, in the year 2015, a programmer have sent me an updated code. With the minimal changes, which mostly are update of the names of Tkinter modules, the code works.

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Sometimes I want to read a web page without its design “improvements”. In many case it is enough to switch off css, and in firefox this functionality is built-in. Shift+F7 to get the developer tools. Thanks stackoverflow for the hint.

After upgrading the local Linux system, my python paramiko (ssh protocol implementation) program stopped working, with the error message:

CTR mode needs counter parameter, not IV

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GNU FriBidi is an implementation of the Unicode Bidirectional Algorithm (bidi). There is a Python binding PyFribidi, but it is not complete. What I need is not a visual presentation of a string, but information where direction is changing. This function is not provided by the binding, therefore I’ve made an alternative using ctypes.

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