Publications by Karsten W.
Large Matrix Multiplication: DuckDB vs. SQLite
On my laptop with 16 GB RAM, I would like to perform a matrix-vector multiplication with a sparse matrix of around 10 million columns and 2500 rows. The matrix has approximately only 2% non-zero entries, but this are still 500 million numbers and the column/row information, too large to work comfortably in-memory. A while ago, I tried using sqlite ...
2342 sym R (3333 sym/6 pcs)
Using chatGPT in the teaching of R
I am currently focalising an introductory course in programming with R within my organisation. We use datacamp.com as a resource and meet online once a week to share. This week my input was an interaction with chatGPT, see below. My impression is that AI can be quite helpful in learning a programming language. Especially if you can ask good quest...
4534 sym R (217 sym/6 pcs) 1 tbl
Getting acquainted with Mastodon — Instances
Elon Musk has to buy Twitter after all. I took this as an opportunity to look at Mastodon at the weekend, a decentralised alternative. TL/DR: super! What I had to understand first was the concept of an “instance”. My first impression is that you can compare a Mastodon server to an email server. Imagine that in order to write emails, you would...
3348 sym R (690 sym/4 pcs) 1 tbl
Play & Analyse Wordle Games
So now I, too, wrote an R package with functions that make playing Wordle easy. English and German Wordle Games are supported. Installation You will need the statistical software environment R. See here for installation notes. To install this github repository, run the following code at the R console: install.packages("remotes") library(remotes)...
6005 sym R (925 sym/9 pcs) 1 tbl
inkblot: an alternative to stacked bar graphs
Sometimes it is not easy to get useful information from a stacked bar chart, see for instance this blogpost at Support Analytics.So-called inkblot charts, as discussed at Kaiser Fung’s Junk Charts, allow the reader to focus on the evolution of a time series.Now how to make this kind of charts with R? I asked on StackOverflow. The given answers ...
941 sym R (297 sym/1 pcs) 2 img
Rosetta language popularity
Rosetta Code is a community wiki which presents how to solve various programming tasks by different programming languages. Thus, it serves as a dictionary between programming languages, but also as cookbook of programming recipes for a specific language.One unsolved (until today) programming task for R was to rank languages by popularity. I worke...
1441 sym R (1017 sym/3 pcs)
use R! 2010 conference — reflections
From July 20-23, this year’s use R! conference took place in Gaithersburg near Washington. I attended the conference as part of my holidays in the U.S. and had a good time there. I met some people, even though that is not the easiest thing for me to do, and I got some inspirations and ideas I outline below:Stat appsOne speaker mentioned „stat...
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Tuning Notepad++
Here are some tricks I collected for making Notepad++ a more comfortable text editor for me in general in for the R programming language in particular.Switch between tabs in Notepad++ with Ctrl-PageUp/DownNotepad++’s default behaviour is to use Ctrl+(Shift)+Tab for tabbing between different text files. This was very annoying to me,because other...
1192 sym
head and tail for strings
The functions head and tail are very useful for working with lists, tables, data frames and even functions.But they do not work on strings. It is easy to define such functions> strtail <- function(s,n=1) { + if(n strhead <- function(s,n) { + if(nand start using them:> strhead("abc", 1) [1] "a" > strhead("abc", -1) [1] "ab" > strtail("abc", ...
807 sym R (195 sym/2 pcs)
Index decomposition with R
Few days ago, I finally finished a small package ida. It enables you to analyse contributions of underlying factors to the change in an aggregate, using methods based on index number theory. These methods have become popular by, but are not restricted to, investigating the change of CO2 emissions.Here is a chart that shows what the change of popu...
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