http://phildawes.net/blog Mostly programming with a few bits of other stuff Mon, 11 May 2009 16:10:29 +0000 http://backend.userland.com/rss092 en I found an excellent and short introductory tutorial pdf on principal components analysis (PCA). It provides a good overview of the following concepts in a particularly intuitive manner: 1) Mean Average 2) Standard Deviation 3) Variance 4) Co-Variance 5) Matrix transformations 6) Eigenvectors & EigenValues 7) Principal Component Analysis Unfortunately I found the eigenvectors bit a bit heavy ... http://phildawes.net/blog/2009/05/11/intuitive-overview-of-principal-components-analysis-pca/ I program in Python, Javascript and Factor on a roughly daily basis. My experience is that I can write functions/methods quicker in Python and Javascript than I can in Factor, but that my Factor code ends up being of considerably higher quality. By higher quality I mean that it's better ... http://phildawes.net/blog/2009/03/30/factor-makes-you-write-better-code/ I don't use python that much any more for my own projects, and so it shouldn't be any surprise to me that I missed one of the most exciting developments: Somebody else has done a python refactoring library! Rope looks tres cool. The problem with bicyclerepairman was that after it did just ... http://phildawes.net/blog/2009/02/26/somebody-does-a-better-bicyclerepairman/ Over the last few years I've read a number of books on stock trading but despite this I never really felt compelled to risk any of my own money on the markets. Then in October I discovered that spread betting offers a cheap way to test the water on a small ... http://phildawes.net/blog/2008/12/12/spread-betting/ Last night I switched to using the Disqus service for comments on this blog and I must say I'm pretty impressed so far. The reason for the switch is that I'm just not staying on top of wordpress upgrades and tweaks and so ideally I'd like to replace my current ... http://phildawes.net/blog/2008/10/01/disqus-comments/ I'm currently building an early release of the webapp database project I've been working on in my spare time. The app is predictably written in factor which has a neat deployment mechanism: you create an image file with just the compiled code that you need to run the app and ... http://phildawes.net/blog/2008/09/29/really-simple-html-templating-in-factor/ Continuing on from yesterday evening, I had a bit of time tonight in front of the telly so I implemented the rest of the fast-search functionality in factor using the assembler code from the previous post. The first step was to create the simple bloom filter for sending to the ... http://phildawes.net/blog/2008/09/12/searching-arrays-in-x86-assembler-with-a-bloom-filter-pt-3/ This is a continuation of the previous post Thanks to the commenters who suggested using other datastructures rather than an unordered array. The reason I'm going for linear search is that it allows the searching of an index sorted for other purposes. The fewer indexes I use, the less data has ... http://phildawes.net/blog/2008/09/11/searching-arrays-in-x86-assembler-with-a-bloom-filter-pt-2/ I'm currently writing what amounts to an olap database in factor in my spare time, which is a pretty interesting project. Actually spare time is limited now that I have a child but factor is affording me a pretty good productivity compared to python and scheme so it's probably net-par ... http://phildawes.net/blog/2008/09/10/searching-arrays-in-x86-assembler-with-a-bloom-filter/ Factor ships with a gui ide, but I prefer to use the command line listener REPL within an emacs buffer for my coding. The advantage is that it's more tightly integrated with emacs - e.g. I can send blocks of code to the repl with keypresses. The downside is the ... http://phildawes.net/blog/2008/09/05/nesting-repls-in-factor/