dinsdag 16 mei 2017


Playing around with scalable vector graphics (.svg), that is text files describing shapes like cubes, rectangles etc. Important for creating charts using D3, data driven documents. For manipulating .svg I use Inkscape, an open source alterbative for Adobe Illustrator. Available for Windows, Mac and Linux at: https://inkscape.org/en/

dinsdag 9 mei 2017



Bought a 32 GB USB drive….that is a complete hard drive! In stead of dual booting Linux from the hard drive, you can boot from the USB in persistent mode, and saving your work and settings. In reading/writing or booting speed is not really different from dual booting. This Philips USB 3.0 Circle 32 GB (compatible with USB 2.0) reads at 55MB/s and writes 10Mb/s. In order to speed up you can run the whole thing in RAM.


Booting from USB is with UEFI a bit more difficult. Generally Ubuntu live start from UEFI with secure boot on. However installing a module in the kernel that is not signed (for example bcmwl-kernel-source, for wireless) is blocked. Let’s disable secure boot. Perfect working, however if you want to start a persistent live Ubuntu then you need to start from UEFI with CSM, because the Ubuntu .iso is a hybrid, and Compatibility Support Module (CSM) provides legacy BIOS compatibility. 

So start up the system with: disable secure boot and fast boot, and enable UEFI with CSM.



To make the USB booting persistent use mkusb. Choose the image, select the drive, tag UEFI and persistent. However when working on HP, mine is HP Elite 820, choose MSDOS partition table not the GUID partition table (GPT), which is standard for UEFI, because HP likes MSDOS better, it seems.

Now I am not only booting into Ubuntu from a portable hard drive, which I can carry along and use it on any machine.

woensdag 12 april 2017

My bot ALEXA: from news-update to reading mail

Amazons software for bot Alexa is ported to Raspberry Pi. It is a nice experience asking for the news (BBC or NYTimes), listen to the emails I just received.

Installing is a piece of cake.
Here is the recipe: How to Build Your Own Amazon Echo with a Raspberry Pi .
Two problems after installing:
- I cannot get the wakewordagent working; it means that instead of yelling ALEXA... I now have to push the button 'listen' to start my question.
- of course you want to use your local settings; here is howto: Using outside the US . 
  The time zone can be set, but not the location; it does accept only US, GB and DE zip codes. I am stick with Dusseldorf weather.



dinsdag 3 januari 2017

The Electronic Barometer

This goes beyond data journalism. It is a project about the Internet of Things, studying the relationship between measurement/observation, data and storing data, and finally retrieving, analyzing and visualizing data if possible real time. Here is the story.

maandag 2 januari 2017


In part 1 we discussed publishing real time data, in part 2 I highlighted storing data in a database and publishing them on a blog. In the last part 3 of this series I will pay attention to retrieving data from the database and visualizing the query results.
The simplest way to retrieve data from MYSQL is installing phpMyAdmin, which gives you complete control of the database, tables and queries. phpMyAdmin makes building a query and exporting it to .csv very easy. The exported .csv can be used for further analysis with for example Excel and visualizing with Google.
More interesting is to make a direct connection to the database from R, making the query, analyze and visualize directly from R. Finally, I pay attention to publishing these results online with plot.ly rest API.


It is nice to read real time the changes in the pressure as an indication of changes in the weather. However, the observations once published are lost.  It would be much better to store the measurements as data in for example MYSQL and publish the data from the database in Wordpress.