data scientist, developer, open data
mostly C++, R packages
I develop R packages for accessing and analysing open spatial data, with a particular focus on urban planning and transport. I am a founding member of Active Transport Futures, and the lead developer of moveability.city, a platform for open-source, open-access interactive visualisations of urban moveability.
07 Nov 19
This article was recently published in the Rcpp Gallery, and demonstrates using the RcppParallel package to aggregate to an output vector. It extends directly from previous demonstrations of single-valued aggregation, through providing necessary details to enable aggregation to a vector, or by extension, to any arbitrary form.
25 Oct 19
Activating github two-factor authentication (2FA) offers an indubitable security boost, with one notable side effect--https authentication requires entering a Personal Access Token instead of password. This entry explains how I reconfigured my git push commands with 2FA to be able to enter my password once again, instead of a random 32-character token.
04 Jul 19
I recently encountered a problem while bundling an old C library into a new R package. The library itself depends on, and includes, an external "dictionary" in plain text format used to construct a large lookup table. The creators of this library of course assume that this dictionary file will always reside in the same directory as the compiled object, and so can always be directly linked. The `src` directory of R packages is, however, only permitted to contain source code, which text files definitively are not. This blog entry is about where to put such files, and how to link them within the source code.
06 Jun 19
Caching is implemented because it saves time, generally by saving the results of one function call for subsequent reuse. Background processes are also commonly implemented as time-saving measures, through delegating long-running tasks to "somewhere else", allowing you to keep focussing on whatever (un)important things you were doing in the meantime. This blog entry describes how to combine the two to save double time through caching via background processes.
07 May 19
C++ templates are really useful. Templates allow you to code a function able to accept arguments of different types that can't necessarily be known until compile time. There is, however, no such thing as an Rcpp template -- all inputs and outputs must have defined types. This blog entry is about how to maximise the usefulness of C++ templates in an Rcpp context.
06 May 19
This site is built with zurb foundation, because i had read that it did everything that hugo could, but that final products were more lightweight and flexible. Plus i had no idea about it, and learning something new is sometimes worthwhile. I was also frustrated that standard hugo advice seemed to be, ''oh, just pick a template and off you go,'' yet there is surprisingly little advice on how to modify any given template, let alone how to start from scratch. It turned out that foundation at least made starting from scratch fairly easy, and so this entry is about that process.
Copyright © 2019 mark padgham