http://fseoane.net/blog Tue, 09 Mar 2010 15:30:17 +0000 http://backend.userland.com/rss092 en LibSVM is a C++ library that implements several Support Vector Machine algorithms that are commonly used in machine learning. It is a fast library that has no dependencies and most machine learning frameworks bind it in some way or another. LibSVM comes with a Python interface written in swig, but ... http://fseoane.net/blog/2010/fast-bindings-for-libsvm-in-scikitslearn/ Yesterday we had an extremely productive coding sprint for the scikits.learn. The idea was to put people with common interests in a room and make them work in a single codebase. Alexandre Gramfort and Olivier Grisel worked on GLMNet, Bertrand Thirion and Gaël Varoquaux worked on univariate feature selection and ... http://fseoane.net/blog/2010/scikitslearn-coding-spring-in-paris/ Today I released the first public version of Scikit-Learn (release notes). It's a python module implementing some machine learning algorithms, and it's shaping quite good. For this release I did not want to do any incompatible changes, so most of them are just bug fixes and updates. For the next release, ... http://fseoane.net/blog/2010/scikit-learn-01/ This week we created a sourceforge project to host our development of scikit-learn. Although the project already had a directory in scipy's repo, we needed more flexibility in the user management and in the mailing list creation, so we opted for SourceForge. To be honest, after using git and Google Code ... http://fseoane.net/blog/2010/scikit-learn-project-on-sourceforge/ New job, new code, new city, new colleges. Feels something like this: http://fseoane.net/blog/2010/after-holidays/ This week I arrived to the place where I will be working the following two years: Neurospin. It's a research center located 20 km from Paris, and so far things are going smoothly: the place is beautiful, work is great and food is excellent. Well OK, I do miss some things ... http://fseoane.net/blog/2009/neurospin-winter-in-paris-is-not-funny/ Nice thing about winter in Granada is, that even in the coldest days, the sky is always blue. http://fseoane.net/blog/2009/last-and-cold-days-in-granada/ My new job is about managing an open source package for machine learning in Python. I've had some experience with Python now, but I am a total newbie in the field of machine learning, so my first task will be to find a good reference book in the subject and ... http://fseoane.net/blog/2009/learning-machine-learning/ I'm extremely glad that finally I am moving to Paris to work as part of the INRIA crew. I'll be working with Gael Varoquaux and his team in an extremely cool Python related project (more to come on this in the following weeks). Granada has been a great place for me on the last ... http://fseoane.net/blog/2009/moving-to-paris/ Google Summer of Code program is officially over. It has been four months of intense work, exciting benchmarks and patch reviewing. It was a huge pleasure working with you guys! As for the project, I implemented a complete logic module and then an assumption system for sympy (sympy.logic, sympy.assumptions, sympy.queries). I ... http://fseoane.net/blog/2009/summer-of-code-is-over/ I managed to overcome the overhead in ask() that arises when converting between symbol and integer representation of sentences in conjunctive normal. The result went beyond what I expected. The test suite for the query module got 10x times faster in my laptop. From 26 seconds, it descended to an impressive ... http://fseoane.net/blog/2009/speed-improvements-for-ask-sympyqueriesask/ Today I've been doing some speed improvements for the logic module. More precisely, I implemented an efficient internal representation for clauses in conjunctive normal form. In practice this means a huge performance boost for all problems that make use the function satisfiable() or dpll_satisfiable(). For example, test_dimacs.py has moved from 2.7 ... http://fseoane.net/blog/2009/logic-module-improving-speed/ This commit introduced a new module in sympy: the refine module. The purpose of this module is to simplify expressions when they are bound to assumptions. For example, if you know that x>0, then you can simplify abs(x) to x. This code was traditionally embedded into the core, but now this ... http://fseoane.net/blog/2009/refine-module/ The query module is finally in the main SymPy repository. I made substantial changes since last post, most of them at the user interface level (thanks to Vinzent and Mateusz for many insightful comments). Main function is ask(), which replaces the old expression.is_* syntax. You can ask many things. For example, ... http://fseoane.net/blog/2009/query-module-finally-in-trunk/ After some failed attempts, I just found how to change the language settings dynamically in django, and I thought it could be useful to someone. Just use function activate() from django.utils.translation. For example: [code lang="python"] from django.utils.translation import activate activate('es-ES') [/code] will change global language settings to 'es-ES' (Spain spanish). I use it because I ... http://fseoane.net/blog/2009/django-change-language-settings-dynamically/ Three months after I began to write sympy.queries, I feel it's about time to include it in sympy's trunk, so today I sent for review 4 patches that implement the complete query module. It's been a lot of fun, but it has also caused me some headaches ... specially last month ... http://fseoane.net/blog/2009/merging-the-query-system-before-euroscipy/ The 0.6.5 release of SymPy is taking longer than expected because some bugs in the testing framework, so my query module is not merged into trunk (yet). In the meantime, I am implementing a refine module (very little code is available yet). The refine module implements a refine() function (better names ... http://fseoane.net/blog/2009/refine-module-proof-of-concept/ Last days I've been busy preparing the first public beta of SymPy 0.6.5. Most of the time was spent solving a bug that made documentation tests fail under python2.4, but now that this is solved, I hope that by the end of the week we could have a final release. When ... http://fseoane.net/blog/2009/preparing-a-new-release/ Background: DPLL is the algorithm behind SymPy's implementation of logic.inference.satisfiable After reading the original papers by Davis & Putnam [1], I managed to implement a more efficient version of the DPLL algorithm. It is 10x times faster on medium-sized problems (40 variables), and solves some wrong result bugs [2]. As a side ... http://fseoane.net/blog/2009/efficient-dpll-algorithm/ After some hacking on the queries module, I finally got it right without the limitations of past versions. You can check it out from my repo http://fseoane.net/git/sympy.git, branch master. It now relies even more on logic.inference.satisfiable(), which is just an implementation of the DPLL algorithm. Bad news is that (my implementation ... http://fseoane.net/blog/2009/queries-and-performance/