mages' blog

Notes from the Kölner R meeting, 14 October 2016

Last Friday the Cologne R user group came together for two talks and a quiz at Eye/o, the company behind Adblock Plus, in Köln-Ehrenfeld. Eye/o were a great host, offering nibbles and drinks to warm up the event and pizza at the end.

Cologne R user meeting at Eye/o

The first talk was given by Jiddu Alexander, a physicist turned freelance data scientist. Jiddu gave an introduction into the tidyverse. He presented the concept of tidy data, and how the tidyverse bundle can be used to manage multiple models. Furthermore, he explained the concept of learning curves for model selection. Jiddu's slides are available from his web site.

Jiddu Alexander explaining learning curves

Next up was Nils Glück to share his experience on performance profiling. R code often grows from a small idea for a specific task to a longer and longer script as more and more ideas and use cases are added. Occasionally, we end up with a long and poorly documented script that 'does the job' but has become slow. Finding the bottlenecks and addressing them is good short term remedy. Nils showed us how the Rprof function of the utils package can be used to understand the performance profile of R code. Furthermore, the microbenchmark package with a function of the same name can then be used to test new approaches for a code block.

Nils Glück quoting others who are not bothered about performance

To bridge the time for the pizzas to arrive our host Kirill had prepared a little R quiz: Could we guess the output of simple R statements? Well, it is more difficult than you might think. Kirill had a great selection of quirky one-liners, which he had collected over time and borrowed from the fabulous R Inferno book by Pat Burns.

Next Kölner R meeting

The next meeting will be scheduled in about three months time. Details will be published on our Meetup site. Thanks again to Eye/o for their support.

Please get in touch, if you would like to present at the next meeting.

Next Kölner R User Meeting: Friday 14 October

The 19th Cologne R user group meeting is scheduled for this Friday, 14 October 2016. We have three talks, followed by networking drinks.

• Introduction to the tidyverse tools - Jiddu Alexander
  
• Performance profiling and improvement in R - Nils Glück
  
• Batch processing of R-Scripts with Excel - Klaus Jacobi
  

Venue: Eyeo GmbH, Lichtstraße 25, 50825 Köln

For further details visit our KölnRUG Meetup site.

Notes from past meetings are available here.

Notes from 4th Bayesian Mixer Meetup

Last Tuesday we got together for the 4th Bayesian Mixer Meetup. Product Madness kindly hosted us at their offices in Euston Square. About 50 Bayesians came along; the biggest turn up thus far, including developers of PyMC3 (Peadar Coyle) and Stan (Michael Betancourt).

The agenda had two feature talks by Dominic Steinitz and Volodymyr Kazantsev and a lightning talk by Jon Sedar.

Dominic Steinitz: Hamiltonian and Sequential MC samplers to model ecosystems

Dominic shared with us his experience of using Hamiltonian and Sequential Monte Carlo samplers to model ecosystems.

Volodymyr Kazantsev: Bayesian Model Averaging

Finding the 'best' model was Volodymyr's challenge. He tried various R packages (BMA, BMS and BAS) for Bayesian model averaging, with various degrees of success.

Jon Sedar: Easier Plate Notation in Python using Daft

Finally, Jon gave a brief overview on Daft, a nifty Python package for creating graphs, or plate notation.

Next meeting

The next Bayesian Mixer Meetup meeting is already scheduled for 21 October. We will be back at Cass Business School, with two talks:

• Darren Wilkinson: Hierarchical Bayesian Modelling of Growth Curves inc Stochastic Processes
• Peadar Coyle: Advanced PyMC3