Round 16: Two Keys And A Bit Of Odd Meter / Zed Shaw

What you'll be doing is using chords to link two keys together so thatyou play Ionian in one key, and then Lydian in the next key. I'llsuggest a few example chord changes, a song structure, and then alsotalk about odd meters for the optional challenge.

The Challenge

Ionian and Lydian are very close modes, with only one note different(the sharp 4). This means you can't really just combine the two modes,since nobody could really hear the difference. Instead, you have tochange keys in the song, purposefully going from Ionian in one key toLydian in another. There's a few ways you can do this, which I'll getinto in the lesson section.

Indexing and retrieving lots of (biological) sequences, quickly / Titus Brown

These days, molecular biologists are dealing with lots and lots ofsequences, largely due to next-gen sequencing technologies.For example, the Illumina GA2 is producing 100-200 million DNAsequences, each of 75-125 bases, per run; that works out to 20 gb ofsequence data per run, not counting metadata such as names and qualityscores.

Storing, referencing, and retrieving these sequences is kind ofannoying. It's not so much that the files themselves are huge, butthat they're in a flat file format called 'FASTA' (or FASTQ), with noway to quickly retrieve a particular sequence short of scanningthrough the file. This is not something you want to do on-demand orkeep in-memory, no matter what BioPython says ;).

So everyone working with these sequences has evolved one way oranother to deal with it. A number of different approaches have beenused, but they mostly boil down to using some sort of database toeither index or store the sequences and associated metadata. It won'tsurprise you to learn that performance varies widely; that benchmarksare few and far between; and that many people just use MySQL, eventhough you can predict that using something like MySQL (or really anyfull-blown r/w database) is going to be suboptimal. This is becauseFASTA and FASTQ files don't change, and the overhead associated withbeing able to rearrange your indices to accomodate new data isunnecessary.

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/ Андрей Попп

Управление проектами в Емаксе / Александр Соловьев

У Емакса какое-то подобие проектов из коробки появилось только в 23 версии, и тоочень простое - только переменные директорий (directory variables, что-то типаfile variables, только хранящиеся в отдельном файле - .dir-locals.el). Побольшей части потому, что ?ber-решения нету, и разным людям нравятся разныерешения. Вот я и решил вкратце рассказать о том, что нравится мне.

Пару лет назад я прочитал статью в каком-то блоге об одном из подобных решений ипопробовал его использовать. Как-то это решение (это был eproject, что ли) неприжилось и я пош?л искать альтернативы. Перепробовав какое-то количество, явзял project-root, прикрутив к нему несколько понравившихся фич от другихпроектов. Теперь можно сказать, что мне действительно удобно - использую этуштуку уже больше года и доволен. :)

Вся идея заключается в том, что вручную указывать путь к проекту (как этосделано в большинстве - если не всех - IDE) - не очень удобно. У большинствапроектов есть какой-то характерный файл (или набор файлов) в корне. К примеру,manage.py у джанговых проектов, или директория .hg у проекта, который лежитв репозитории меркуриала. В результате можно определять проект по наличию такихфайлов; моя текущая конфигурация выглядит примерно таким образом:

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Shed 8: Memorizing Triads And Fourths / Zed Shaw

The way I'm going to show you how to memorize this is a littledifferent from how most musicians are taught. That's because I'm aprogrammer, so I try to find easier ways to memorize the few things Ineed to know. Rather than memorize a ton of useless information, I lookfor a few patterns that and mnemonics that help you memorize theinformation and use it.

Cycle Of Fourths

First, let's do the cycle of fourths since that's the easiest. What'smeant by the "cycle of fourths" is you pick a root note C, that's thekey you're in. Then you pick the 4th note in that scale, and move tothe next key F. From F you pick the 4th note and move to that key andyou're in Bb. For example, if you were to have this chord progression:

Becoming The Center Of The Universe / Zed Shaw

2010-03-25 : Becoming The Center Of The Universe

I am in the process of shutting down this site as a blog and converting it intoa “Center Of The Universe” aggregator for all the various projects I’m doingaround the internet. I like to change things up about once a year just toexplore new and interesting things, and this time around I’m going to stop doingthings outside of zedshaw.com and open source. I’ll probably release opensource here and there, since it’s in my blood, but it’ll be mostly thing relatedto music or the sites I create.

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Cassandra in action / Jonathan Ellis

There's been a lot of new articles about Cassandra deployments in the past month, enough that I thought it would be useful to summarize in a post.

Ryan King explained in an interview with Alex Popescu why Twitter is moving to Cassandra for tweet storage, and why they selected Cassandra over the alternatives. My experience is that the more someone understands large systems and the problems you can run into with them from an operational standpoint, the more likely they are to choose Cassandra when doing this kind of evaluation. Ryan's list of criteria is worth checking out.

Digg followed up their earlier announcement that they had taken part of their site live on Cassandra with another saying that they've now "reimplemented most of Digg's functionality using Cassandra as our primary datastore." Digg engineer Ian Eure also gave some more details on Digg's cassandra data model in a Hacker News thread.

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Course announcement: Analyzing Next-Generation Sequencing Data / Titus Brown

Analyzing Next-Generation Sequencing Data

May 31 - June 11th, 2010

Kellogg Biological Station, Michigan State University

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Round 15: Lydian Mode For Greater Good / Zed Shaw

Included in this round is a copy of theUS Navy Basic Music Manual which is an excellent free manual that covers a wide range ofpractical music theory. I'll be using their way of describing scales and modes since it's simple to understand, but if you have your own way then go for it.

The Challenge

For this round we are looking to get you into using the Lydian modewhere you'd normally use the Ionian mode. Your challenge is to craftanother simple 3 or 4 chord progression that lets you play the Lydianmode and either emphasize the sharp 4 note (F# in a C Lydian mode) orsimply craft a regular major mode progression and play Lydian on itanyway.

Declarative, context-dependent CSS selectors / Brett Cannon

When I designed Oplop's UI, I knew I needed some way to delineate what step was the active step (which are individually contained within section tags). I went with a class called open since jQuery has its toggleClass() function which makes it like flipping a bit. Plus I could style the steps in CSS with a default for all steps and then specialization with the section.open selector for that one step that was currently open. This allowed me to have the UI-specific stuff in regards to what was (not) the currently open step be declared in a CSS file.

But there was a shortcoming with how I did it. Having only two selectors gave me only binary control over the UI in terms of steps. What I really needed was three possible states; not yet opened/upcoming, open, and opened previously/closed. I could have used some JavaScript to easily tweak the CSS as I moved about, but it was so nice to have the UI stuff in a declarative format in the CSS file and not interwoven in my JS code that I didn't want to. This was made especially obvious to me thanks to the Restart button which would need to unroll any changes made by the user; the less I had to keep track of the better as that lessened the chance I missed something.

And then some people complained

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