Stuff Sean Knows

Coding notes and things of interest.

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Mathematically correct breakfast: How to cut a bagel into two linked halves. 

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Reset your password!

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A/B Testing and Machine Learning

This blog post is a fascinating look at an alternative to traditional A/B testing for new web site features. It has an insightful look at the statistics behind the traditional method and proposes a very simple, and clearly superior, method for testing which is based on a simple algorithm that is trivial to implement. 

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CSS Shapes

This site has some extremely clever examples of drawing shapes with an HTML element and CSS. 

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Counting stuff in bash

I am the WORST at remembering the finer points of command line actions. Here is how you count the output from find (or ls or whatever):

find ./ -name *.pdf | wc -l

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That hits so close to home.

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Sorting multidimensional arrays in PHP5

Here is a small class used to sort by a key in a multidimensional array in PHP5

class MultiDimSortByKeyValue{

   static private $key;

   public static function sort(&$array, $key){

       self::$key = $key;

       usort($array,array('MultiDimSortByKeyValue','compare'));

   }

   private static function compare($a, $b){

      return (strcasecmp( $a[self::$key], $b[self::$key] ));

   }

}

Usage:

MultiDimSortByKeyValue::sort($array, $key)

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Replace shebang!

I am sure that I am late to the game, but here is a solution to portability problems with shell/perl scripts. Instead of:

#!/bin/bash

start scripts with:

#!/usr/bin/env bash (or perl)

This will use the system paths for the interpreters and make the script more portable. Woohoo!