Author Archives: Nelson

Big Data and how Isaac Asimov will have successfully predicted psychohistory

Posted by on May 13, 2012 No comments

A couple of weeks ago, I had the opportunity to attend MarkLogic World 2012.  The overall theme of the conference was converting Big Data into Big Ideas.  Big Data is a paradigm shift for many in the IT industry; briefly, Big Data saves everything, whether it’s usefulness is obvious or not, in hopes that decisions can be made on that data.  In theory, the traditional data model would be unable to make informed decisions because the data set would not be large enough accurately describe super-complex issues.

Psychohistory, then, as defined by Isaac Asimov in his novel Foundation, goes something like this:

Branch of mathematics which deals with the reactions of human conglomerates to fixed social and economic stimuli; implicit in all these definitions is the assumption that the human conglomerate being dealt with is sufficiently large for valid statistical treatment.

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Words With Friends bug

Posted by on April 30, 2012 No comments
TheDailyWTF would be proud

Is an empty string really a misspelled word?

Convert an integer to a sequence of digits in Xquery

Posted by on March 25, 2012 1 comment

I am new to the functional programming paradigm and Xquery. As part of a larger exercise, I wanted to sum the digits of an integer.  The first part of that problem is to solve the smaller problem: convert an integer to a sequence of integers that I can then pass to fn:sum as a parameter.

(: I've declared the function in the nwnu namespace for testing purposes :)
declare function nwnu:number-to-seq($num as xs:integer)
as xs:integer* {
  if($num gt 9) then
    (
      nwnu:number-to-seq(xs:integer(math:floor($num div 10))),
      xs:integer(math:floor($num mod 10))
    )
  else
    $num
};

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Pair Programming

Posted by on March 20, 2012 1 comment
Pair Programming

Nothing like cracking the whip

JSON.stringify with mapped variables

Posted by on February 6, 2012 1 comment

There are times when I want to create a data structure in Mirth, and output the contents of that data structure while debugging the code.  Luckily, JSON.stringify() is available not only in modern browsers but also in Mirth.

var o = {
  mrn: '8675309',
  labs: [
    'blood bank',
    'microbiology',
    'toxicology'
  ]
};

console.log(JSON.stringify(o, null, '\t'));

However, there are any types of Mirth mapped variables, the JSON.stringify() method blows up on itself with a message similar to

DETAILS:    Java class "[B" has no public instance field or method named "toJSON".

This is how we fix it.

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Introduction to web scraping with Node.js

Posted by on November 8, 2011 2 comments

The internet has a wealth of freely available information in difficult to consume formats.  For example, ClicheSite has lists of cliches, euphemisms, and other phrases that are just perfect for a hangman or Wheel of Fortune game.  Coincidentally, I wanted to write such a game to learn some new technologies, so I wrote a short, simple Node.js script to scrape some pages for those phrases.  In this tutorial, I’ll discuss how to make an HTTP request and get a page’s HTML, how to parse the HTML for specific information, and why you would and would not want to do this in the first place.
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Swap object keys and values in Javascript

Posted by on October 11, 2011 1 comment

There are times when I would like to do work with the values in a Javascript object used as a hash map.  For example, sometimes I’d like to iterate over the values and perform an action on them, or perhaps check that a value exists in the hash map.  In this post, I’ll write a function that inverts the keys and values in a hash map, give a couple of examples in regards to how and why you’d want to do that, and explain the short-comings of the approach.

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Introduction to memoization with Javascript

Posted by on September 25, 2011 4 comments

Memoization is a function optimization technique used to avoid remaking calculations in subsequent function calls.  The classic example, which we’ll demonstrate here, is the factorial function.  5! = 5 * 4 * 3 * 2 * 1… factorials are recursive in nature if we give it some thought.  5! = 5 * 4! and 4! = 4 * 3! and so on.  By recognizing this pattern, we can also recognize that if we calculate 5! and save the results, then we should not have to recalculate it when we do 7!.  Instead of calculating 7! by 7 * 6 * 5 * 4 * 3 * 2 * 1, we’ll calculate it by 7 * 6 * 5!.

We’ll first examine the naive approach and then the memoization method.  All in Javascript, and all with code samples…
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Maintain a running list of your external IP address

Posted by on August 7, 2011 1 comment

At home, I have a consumer level cable internet service.  I actually do not know if I have a dynamic IP address or a static IP address because I haven’t really cared enough to ask my ISP.  I would assume that I have a dynamic IP address since most ISPs charge a premium for a static IP address, but since I don’t know for sure I thought I would find out for myself.

Using http://whatismyip.com ‘s “automation” page, Perl, and cron, I am going to maintain a list of my external IP addresses.  Not only will this answer the original question, but I can also gather some additional information, such as how often my IP address changes and whether or not I can force my IP address to change by disconnecting my modem :) .

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Fixing line breaks in HL7 messages in Mirth Connect

Posted by on July 12, 2011 No comments

Anyone who has worked in the world of healthcare integration or with HL7 knows that if you have seen one HL7 message, you’ve seen one HL7 message.  Now, a common problem with some source systems is that a line break will sneak in the middle of a segment, rendering the whole message invalid.  How many times have you seen this message?

MSH|^~\&|DDTEK LAB|ELAB-1|DDTEK OE|BLDG14|200502150930||ORU^R01^ORU_R01|CTRL-9876|P|2.4
PID|||010-11-1111||Estherhaus^Eva^E^^^^L|Smith|19720520|F|||256 Sherwood Forest Dr.^^Baton Rouge^LA^70809||(225)334-5232|(225)752-1213||||AC010111111||76-B4335^LA^20070520
OBR|1|948642^DDTEK OE|917363^DDTEK LAB|1554-5^GLUCOSE|||200502150730|||||||||020-22-2222^Levin-Epstein^Anna^^^^MD^^Micro-Managed
Health Associates|||||||||F|||||||030-33-3333&Honeywell&Carson&&&&MD
OBX|1|SN|1554-5^GLUCOSE^^^POST 12H CFST:MCNC:PT:SER/PLAS:QN||^175|mg/dl|70_105|H|||F

Notice the “Health Associates” segment? Obviously, this segment invalidates the message.  When this message is sent through a Mirth channel that expects incoming HL7, the message will error out when Mirth tries to parse it.  Here is how we can fix that.

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