Lennart's weblog

Notes about open source software, computers, other stuff.

Author: LCK (Page 8 of 14)

A bioinfomatician on the move...

ProbABEL v0.3.0 released

4 January 2013 / / 0 Comments

On New Year’s day I released version 0.3.0 of ProbABEL, almost two months after the previous release.

This update contains a few small bug fixes, but the most important feature of this new release is that thanks to the work of Maarten Kooyman we have a four to five-fold speed increase for the types of GWAS we run at work. In his e-mail to the GenABEL developers list he explains what he did to achieve this. The take-home-message of it is that you should always look for a suitable library for important tasks of any program you write. The old ProbABEL was based on a self-written matrix class that handled things like matrix multiplication and matrix subsetting. In the new release we make use of the Eigen C++ template library, maintained and developed by people who know much more about fast implementations of linear algebra than we do.

For those of you running Ubuntu Linux (or one of its derivatives and probably also Debian) I have set up the GenABEL PPA (personal package archive) where you can download and install the ProbABEL .deb package and stay up to date with future updates.
ProbABEL is also available for MS Windows, although we don’t have much experience running it on that platform.

Development of ProbABEL (and other members of the GenABEL suite) takes place on this R-forge page. If you are in search of an open source project to contribute to, feel free to contact us!

User support for the GenABEL suite can be found at our forum.

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Tabs and spaces in Emacs

30 November 2012 / / 0 Comments

Recently I added the following lines to my ~/.emacs file:

;; Don't insert tabs when indenting regions
(setq-default indent-tabs-mode nil)

The idea behind disabling the indent-tabs-mode was that (especially) while programming I want any tabs to be converted to spaces. Since different people have different settings for a tab width this seemed like a good choice.
However, once I opened a Makefile I ran into trouble. In a Makefile tabs are a requirement, not an option. Since all my tabs were converted to spaces the moment I saved a Makefile compiling became a nightmare. To solve this problem I added the following to my ~/.emacs file, after the aforementioned statement:

(add-hook 'makefile-mode-hook
          (lambda ()
            indent-tabs-mode t))

This enables tabs again for modes that involve Makefiles.

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The Raspberry Pi runs ProbABEL

21 November 2012 / / 1 Comment

One of the first things I tried on my Raspberry Pi was to compile ProbABEL and see if it runs. Since the Raspberry Pi has an ARM processor I wasn’t sure whether our code was portable to it. Apparently it is! Compiling ProbABEL (r.1027 from SVN) took 30 minutes (single threaded of course) compared to 34 seconds on my Desktop (4 threads on an Intel Core i3 processor), but hey, it worked :-). Surprisingly it also passed all the checks in make check.

Once I hook up some more storage to device I will try to run ProbABEL on some real data. It will be interesting to see how much time it takes to run a linear regression on e.g. chromosome 22 of HapMap3 imputated data for a few hundred samples…

Will the Raspberry Pi be the next platform for GWAS ;-)?

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Enter the Raspberry Pi!

21 November 2012 / / 1 Comment

Two weeks ago I received a Raspberry Pi! The Raspberry Pi is a small computer based not on a “regular” Intel or AMD x86 processor, but on an ARM processor (similar to the ones used in smartphones etc.). The one I ordered is a model B (with ethernet) and 512MB RAM.

The idea behind this nifty little computer is to provide kids with a low-cost but fully functional computer with which they could start learning more about programming. I’m not sure if this goal will be widely met, but for me it worked ;-). Having this little machine (with its case it measures roughly 10 x 6 x 2.5 cm) in my hands and installing Raspbian Linux on an SD card and looking at the terminal as it booted reminded me of the times when I first played with Slackware Linux on a 486. Of course Raspbian (well, Linux in general) is much more advanced than Slackware 7.0 back in 1999/2000 but the not too stellar performance of the graphical desktop is somewhat comparable.

Apart from playing around with it I’m not sure yet what I’m going to use it for. A domotica hub? A small web sserver? Use DosBox to play old games (from even before the 486 era)? We’ll see!

By the way, I order mine on Thursday Novermber 8th and on the Tuesday after that the package landed on my doorstep. Amazing after hearing about people waiting for months for their orders to be shipped. I order mine from New IT. It probably cost a little bit more, but who cares :-).

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ProbABEL 0.2.2 released

21 November 2012 / / 1 Comment

On November 7th I released version 0.2.2 of ProbABEL, a set of programs that allow scientists (usually geneticists and epidemiologists) to run Genome-wide association studies (GWAS) in a fast and efficient way, even on machines with low amounts of RAM.

ProbABEL is part of the GenABEL suite, wich is a set of open source package for statistical genomics. Its main developer is Yurii Aulchenko, my former supervisor at the Erasmus Medical Centre.

This update contains a few small bug fixes and an update of the probabel.pl wrapper script that enables the use of chunked imputation output files as input. For more detailed changes, check the announcement.
For those of you running Ubuntu Linux (or one of its derivatives and probably also Debian) I have set up the GenABEL PPA (personal package archive) where you can download and install the ProbABEL .deb package and stay up to date with future updates.
ProbABEL is also available for MS Windows, although we don’t have much experience running it on that platform.

Development of ProbABEL (and other members of the GenABEL suite) takes place on this R-forge page. If you are in search of an open source project to contribute to, feel free to contact us!

User support for the GenABEL suite can be found at our forum.

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Enabling middle mouse button emulation in Ubuntu 12.10

3 November 2012 / / 0 Comments

A few days ago I installed Ubuntu 12.10 on a 2009 laptop (a Dell Latitude D820). This laptop has a trackpoint (the little nib between the G, B and H keys on the keyboard that functions as a mouse). The trackpoint has its own set of mouse buttons, but, unlike my present Thinkpad, it doesn’t have a middle mouse button.
From my early Linux years I remembered that you could use a simultaneous click on the left and right buttons of a mouse to emulate the click of a middle mouse button. This option had to be set in the Xorg configuration file. My guess was that by now this was no longer needed, but I couldn’t find the appropriate option anywhere in Ubuntu’s settings. It’s quite a shame to see that Gnome/Unity/others(?) remove settings like that.
Anyway, looking around the web I found the solution. The middle mouse butten emulation can be enabled in the Gnome configuration by running the following in a terminal:

gsettings set org.gnome.settings-daemon.peripherals.mouse middle-button-enabled true

It worked immediately!

As an aside, I also had to install the packages nvidia-current and nvidia-settings in order to use the nVidia drivers. Without them using the Unity interface was dead slow, even though the laptop has an nVidia Geforce Go 7400.

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Testing for the presence of the “Eigen” headers using autoconf

27 October 2012 / / 0 Comments

For the ProbABEL project I’m working on I wanted to test for the presence of the Eigen header files using . Eigen is a C++ template library for linear algebra. It basically consists of a bunch of header files. On my PC the Eigen files are installed in /usr/include/eigen3/ since I used the Debian/Ubuntu libeigen3-dev package.

I first tried to test for the headers by simply including 

AC_CHECK_HEADERS([eigen3/Eigen/Dense])

in configure.ac, but that didn’t work:

...
checking eigen3/Eigen/Dense usability... no
checking eigen3/Eigen/Dense presence... no
checking for eigen3/Eigen/Dense... no
...

It turns out that you have to add the following lines to configure.ac:

AC_LANG_PUSH([C++])
AC_CHECK_HEADERS([eigen3/Eigen/Dense])
AC_LANG_POP([C++])

Now I get the following output when running ./configure:

...
checking how to run the C++ preprocessor... g++ -E
checking eigen3/Eigen/Dense usability... yes
checking eigen3/Eigen/Dense presence... yes
checking for eigen3/Eigen/Dense... yes
...

To go into a bit more detail, these are the errors in config.log without the AC_LANG options:

...
configure:4877: checking eigen3/Eigen/Dense usability
configure:4877: gcc -c -g -O2 -Wall conftest.c >&5
In file included from /usr/include/eigen3/Eigen/Core:35:0,
                 from /usr/include/eigen3/Eigen/Dense:1,
                 from conftest.c:67:
/usr/include/eigen3/Eigen/src/Core/util/Macros.h:188:5: error: unknown type name 'namespace'
/usr/include/eigen3/Eigen/src/Core/util/Macros.h:188:21: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token
In file included from /usr/include/eigen3/Eigen/Dense:1:0,
                 from conftest.c:67:
/usr/include/eigen3/Eigen/Core:98:12: error: expected identifier or '(' before string constant
In file included from /usr/include/eigen3/Eigen/Dense:1:0,
                 from conftest.c:67:
/usr/include/eigen3/Eigen/Core:144:18: fatal error: cerrno: No such file or directory
...

It seems to be the case that AC_LANG is set to C instead of C++ and consequently compilation of autoconf’s test programme fails. The AC_LANG_PUSH option forces autoconf to use C++.

Thanks to this post on Stack Overflow I could solve this problem.

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Subversion: merging updates in trunk to a branch

25 October 2012 / / 0 Comments

Yesterday I was working on ProbABEL, an open source package for running GWAS (genome-wide association studies). We use R-Forge and they provide us with a Subversion (SVN) server for revision control.

Some time ago we created a branch in which one of the co-developers is doing some major refactoring of the code. In the mean time I have been fixing bugs and adding new features to trunk. Now that the work in the refactoring branch comes to an end I thought it was high time to integrate the changes in trunk with the changes in the branch so that we can later promote the branch to trunk.

Since I had never done this before I decided to try the merge in the doc directory first, because I knew that in that directory nothing had changes since the branch was created, so all changes from trunk should be imported. At first I followed the SVN book instructions so I went into the doc dir in the branch and ran

$ svn merge ^/pkg/ProbABEL/doc

Unfortunately that didn’t work out. For some reasons conflicts appeared as wel as files that weren’t supposed to be there at all.

Thanks to Google and this blog post I found a solution. It boils down to explicitly telling SVN which revisions to use for the merge.

First I used

$ svn log | grep -C3 branch

to find out at which revision I created the branch:

------------------------------------------------------------------------
r864 | lckarssen | 2012-03-27 17:38:05 +0200 (Tue, 27 Mar 2012) | 1 line

Creating ProbABEL branch for code refactoring

Next I went to trunk and ran

$ svn update
At revision 987.

to find out at which revision trunk currently was. Back in the doc directory in the brach I ran

svn merge -r 864:987 ^/pkg/ProbABEL/doc

to merge al the changes since the branch was split off and it worked like a charm! All changes in trunk applied cleanly.

I then id the same for the other directories which also had changes in the branch. It turns out that when SVN find a conflict it is easier to postpone resolving the conflict because Emacs has a great SVN merge minor mode called SMerge! It highlights your changes vs. the incoming ones and allows you to select a resolution and move to the next conflict with a few easy keystrokes. After all conflicts have been resolved Emacs automtically removes the intermediate files SVN created and you are ready to commit.

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Ubuntu 12.04: LaTeX siunitx package and the correct font in beamer

20 May 2012 / / 0 Comments

When writing scientific text I normally use the siunitx package to typeset numbers (using \num{}) and numbers with units (e.g. \SI{4.0}{TB}) in LaTeX.
Something that bothered me for a while was the fact that when making presentations in Beamer, numbers and units would be typeset in a serif font, whereas beamer uses sans-serif fonts.
The solution is actually documented in the manual, but what to me a while to figure out was that in Ubuntu 12.04 (and therefore in Debian as well, I presume) the version of the siunitx package is lagging compared to what is available on CTAN. Ubuntu 12.04 still has version 1.3a of the siunitx package, which was released in September 2009. For this version the solution is to add the following to the preamble of your document:

\sisetup{obeyfamily=false,mathrm=mathsf,textrm=sffamily}

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