R Error: “Error in readBin(fileR, “integer”, n = Length/2, size = 2, signed = TRUE, : invalid ‘n’ argument”

The following error is an indication that an exceptional I/O error occurred. For instance, permissions denied, out of memory, etc. Normally the syntax of this error would indicate that a required parameter is missing from a function call, but with readBin it appears to be more often an exception. Error in readBin(fileR, “integer”, n = […]

ExtJS Listener Example

Problem You want an Ext component to respond to an event. Solution Use the “listeners” property of the object. Ext.onReady(function() { var trackStore = new Ext.data.Store({ storeId: ‘soundCloudStore’,   proxy: { type: ‘ajax’, url: ‘blues.json’, reader: { type: ‘json’, idProperty: ‘id’ } }, fields:[’duration’, ‘genre’, ‘created_at’, ‘title’, ‘id’] }); trackStore.load( function() { Ext.create(’Ext.grid.Panel’, { title: […]

ExtJS Stacked Bar Chart Example

Problem You want to display a stacked bar chart. Solution Use the Ext.chart.Chart, and set the “series” property, including type: ‘bar’ and stacked: true. Ext.onReady(function() { Ext.define(’ParolePoint’, { extend: ‘Ext.data.Model’, fields: [’state’, ‘entry’, ‘exit’] });   var store = Ext.create(’Ext.data.Store’, { model: ‘ParolePoint’, data : [ {state: ‘Connecticut’, entry:31000, exit:28211}, {state: ‘Maine’, entry:3627, exit:3692}, {state: […]

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Marking time in R

In a previous example, I showed how to find the onset of a single drumbeat, as well as the chord at an instant. This new example extends the method to detect the onset of several notes in a row, and demonstrates some interesting challenges involved in musical transcription. The general process is to read in […]

What is vSphere Hypervisor?

Computer virtualization allows resources from one powerful server to be split among many smaller servers. This lets you manage resources more effectively, e.g. moving memory and CPU resources between virtual machines, turning machines on and off as needed, and moving machines to new hardware with minimal downtime. VMware describes vSphere as their virtualization platform – […]

What is ESX and ESXi?

ESX and ESXi refer generally to two versions of the VMware product line- these are the hypervisors that are part of vSphere. VMware refers to vSphere as a “virtualization platform,” which appears to mean an OS and the administration tools that ship with it. ESX/ESXi are the hypervisors – the critical piece of the operating […]

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Book Review: Envisioning Information, by Edward Tufte

When I purchased Envisioning Information, I expected it to merely discuss the nuances of communication through graphs and infographic-style pictography. Rather, the author is an artist, and describes his work as celebration of the escape from flatland. While artistic, he is concisess, laser-focused on his belief that graphical representations of data must be clear and […]

Architexa Review

Architexa is an Eclipse plugin for code analysis. I tested it on a fairly large application. My expecation going in was that it would only be useful to get up to speed- in fact, the diagramming functionality would help me answer common questions. E.g. Which screens use external services, how much of the project is […]

Scraping Videos with PhantomJS

I’ve been using PhantomJS for some scraping projects – PhantomJS is a headless webkit, packaged to run Javascript scripts. Some of my family are still on a slow connection with a low monthly bandwidth cap- they can’t watch many videos. This is unfortunate given the number of training classes available online (e.g., pattern drafting, in […]

ExtJS Pie Chart Example

Problem You want to display a pie chart. Solution Use the Ext.chart.Chart, and set several properties under the “series” property to render a pie chart. Ext.onReady(function() { Ext.define(’PopulationPoint’, { extend: ‘Ext.data.Model’, fields: [’state’, ‘population’] });   var store = Ext.create(’Ext.data.Store’, { model: ‘PopulationPoint’, data: [{ state:"Alabama", population: 4802740}, { state:"Alaska", population: 722718}, { state:"Arizona", population: […]