PCR's notepad » science

Quick statistics competence assessment

David Dernoncourt — Thu, 18 Mar 2010 16:32:58 +0000

Do you understand the following comic?

If you don’t, your statistical skills require an emergency treatment (unless you actually don’t use statistics) because you are likely to draw erroneous excessive conclusions.
If you do, well, I can’t conclude.

R-project Portable

David Dernoncourt — Thu, 21 Jan 2010 08:21:33 +0000

The guys at R-project tell you that you can run R from a CD or USB drive (so it’s portable), but nowhere they provide you with a really portable version. I.e., you have to actually run the installer then you can make a portable copy of the R folder on your USB key. That’s not exactly practical because if for instance you want to “install” it at work on a restricted computer where you can’t run an installer, you need to start with some homework first…
So for the lazy like me, here is a portable version of R 2.10.1. I made it from a custom installation (as far as I remember it’s like the standard installation without language packs and with only some of the manuals) and it’s in English, of course

Also, note that automatically installing additional packages should work fine on this portable version (I did so with my previous 2.10.0 portable, so no reason it wouldn’t work with that one).

Calculating molar masses quickly and online

David Dernoncourt — Mon, 30 Nov 2009 10:19:39 +0000

Although I’m well aware and used to the fact that you can find anything on Internet, sometimes it still amazes me. Remember the time when you needed to fetch a periodic table of the chemical elements plus (optionally) a calculator to get a molar mass? Then came pieces of software that did it for you, but you still needed to fetch the software. Now, you can find the stuff anywhere on Internet, like at convertunits.com, where you can calculate the molar mass of TNT as easily as you can get the molar mass of potassium. I personally found it when trying to compare the molar mass of sodium salt (58.44 g/mol) vs potassium salt (74.55 g/mol), which is the thing used in salt substitutes like LoSalt.

How to change language in R (Windows version at least)

David Dernoncourt — Wed, 25 Nov 2009 09:10:19 +0000

Like a lot of open-source programs, R comes with the highly annoying “feature” of being extremely localized. Not only does it default to your system’s language, but also it makes it a pain in the neck to manage to change the language: using the “GUI preferences” menu (or whatever it is in your locale, haha ^^) to change the language doesn’t even seem work… (you need to restart R for a language change to apply, but when you restart your custom configuration doesn’t get loaded – awesome)
But, well, someone asked the question on an R mailing list hosted by the University of Newcastle, Australia, and the solution is to run R with the added command line parameter LANGUAGE=en (edit the shortcut to R and add this stuff at the end).

On a side note, the solutioner points out a very common mistake made by localizers:

“Apparently some users want Windows in their native language, but not R.”

Dear localizers, you appear to forget or ignore the fact that some people run your software on their work computer, where they don’t have the choice of their OS nor of their language. You also seem to ignore that in some countries it’s pretty hard to grab a legal non-local copy of Windows. So please, don’t make it hard for users to change your program’s language back to normal (i.e. English). How would you like it if I forced you to read a Google-translated version of this notepad in your local language, hm?