Articles by Derek Jones

I made a mistake, please don’t shoot me

July 31, 2013 | Derek Jones

The major difference between commercial/academic written software is the handling of user mistakes, or to be more exact what is considered to be a user mistake. In the commercial world the emphasis is on keeping the customer happy, which translates into trying hard to gracefully handle any ‘mistake’ the ... [Read more...]

Amount of end-user usage of code in Firefox

July 25, 2013 | Derek Jones

How much end-user usage does the code in Firefox receive over time? Short answer: The available data is very sparse and lots of hand waving is needed to concoct something. The longer answer is below as another draft section from my book Empirical software engineering with R. As always comments ... [Read more...]

Never too experienced to make a basic mistake

April 15, 2013 | Derek Jones

I was one of the 170 or so people at the Data Science hackathon in London over the weekend. As always this was well run by Carlos and his team who kept us fed, watered and connected to the Internet. One of the three challenges involved a dataset containing pairs of ... [Read more...]

R needs some bureaucracy

March 12, 2013 | Derek Jones

Writing a program in R is almost bureaucracy free: variables don’t need to be declared, the language does a reasonable job of guessing the type a value might need to be automatically be converted to, there is no need to create a function having a special name that gets ... [Read more...]

The most worthwhile R coding guidelines I know

March 2, 2013 | Derek Jones

Since my post questioning whether native R usage exists (e.g., a common set of R coding patterns) several people have asked about coding/style guidelines for R. My approach to style/coding guidelines is economic, adhering to a guideline involves paying a cost now for some future benefit. Obviously ... [Read more...]

Does native R usage exist?

February 22, 2013 | Derek Jones

Note to R users: Users of other languages enjoy spending lots of time discussing the minutiae of the language they use, something R users don’t appear to do; perhaps you spend your minutiae time on statistics which I don’t yet know well enough to spot when it occurs). ... [Read more...]

My R naming nemesis

December 17, 2012 | Derek Jones

When learning a new language I try to make an effort to write it like a native developer. R has one language feature that has been severely testing my desire to write like a native and this afternoon I realized that most of the people reading my code will also ... [Read more...]

Distribution of uptimes for high-performance computing systems

November 28, 2012 | Derek Jones

Computers break down every now and again and this is a serious problem when an application needs runs on thousands of individual computers (nodes) plugged together; lots more hardware creates lots more opportunity for a failure that renders any subsequent calculations by working nodes possible wrong. The solution is checkpointing; ... [Read more...]

Break even ratios for development investment decisions

October 22, 2012 | Derek Jones

Developers are constantly being told that it is worth making the effort when writing code to make it maintainable (whatever that might be). Looking at this effort as an investment what kind of return has to be achieved to make it worthwhile? Short answer: The percentage saving during maintenance has ... [Read more...]

Agreement between code readability ratings given by students

October 13, 2012 | Derek Jones

I have previously written about how we know nothing about code readability and questioned how the information content of expressions might be calculated. Buse and Weimer ran a very interesting experiment that asked subjects to rate short code snippets for readability (somebody please rerun this experiment using professional software developers). ... [Read more...]

Sequence generation with no duplicate pairs

October 4, 2012 | Derek Jones

Given a fixed set of items (say, 6 A, 12 B and 12 C) what algorithm will generate a randomised sequence containing all of these items with any adjacent pairs being different, e.g., no AA, BB or CC in the sequence? The answer would seem to be provided in my last post. ... [Read more...]
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