The E8 root polytope, its vertices and its edges The E8 root polytope, also known as the \(4_{21}\) polytope is a 8-dimensional polytope. The Cartesian coordinates of its vertices ar... [Read more...]

Some of my 3D animations start with a 4D object (such as a polytope) and I project it to the three-dimensional space with a stereographic projection. For example, the hyperbolic gircope. For this animatio... [Read more...]

This post is a demonstration of the cxhull and gyro packages. I will use these packages (and others) to draw an hyperbolic version of the stereographic projection of a convex 4D polytope, the gircope or ... [Read more...]

The problem Suppose you want to get the volume under a surface but you only have some points on this surface. For the illustration, I will take the surface defined by \(z = \exp\bigl(-(x^2 + y^2)\bi... [Read more...]

I am not a big fan of the built-in filters of DT. I prefer the ones below, made with the help of the JavaScript library select2. First, download the files sele... [Read more...]

My package gyro has been freshly released on CRAN. I implemented the ideas given in this blog post in this package. It has a short vignette. The gyrodemos function provides s... [Read more...]

In this blog post I introduce three small RStudio addins I did. ‘bracketify’ I prefer subsetting with the double brackets than with the dollar in R, because this is more readable in RS... [Read more...]

In a recent post I explained how to decorate a surface with moving colors with the Python library PyVista. Here I expose this method for the R package rgl. I will take a Hopf... [Read more...]

The gifski command-line utility is a great tool to make a GIF animation from a series of png files. At my work I’m using a laptop with Windows 10 and I don’t have admin rights. I don’t know how to install... [Read more...]

Four years ago I wrapped the C library Qhull in a Haskell package. Thanks to Qhull, this package can do some convex hulls and some Delaunay tessellations. The Qhull library also allows to do some ... [Read more...]

Eric Dunipace recently released a new package on CRAN: RcppCGAL. It allows to link to the C++ library CGAL in Rcpp. The CGAL library provides an extensive set of algorithms for computational geome... [Read more...]

We will firstly show how to clip an isosurface to a ball with R, and then, more generally, how to clip a surface to an arbitrary region. In the last part we show how to achieve the same with Python. ... [Read more...]

I do not well remember, but it seems to me I faced some difficulties when I tried to use Shiny bookmarking to save and restore the state of a Shiny app. These difficulties arose when there were some rende... [Read more...]

My new package ‘gfiExtremes’ is on CRAN now. So it is time to present it. This package allows to get confidence intervals about the quantiles of any reasonable distribution (although... [Read more...]

Throughout this article, one considers the balanced one-way ANOVA model with a random factor (group). The between standard deviation and the within standard deviation are denoted by \(\sigma_{\mathrm{b}}\... [Read more...]

Updated title: Haskell is fast, but Julia is faster (see updates at the end). My R package ‘HypergeoMat’ provides a Rcpp implementation of Koev & Edelman’s algorithm for the eval... [Read more...]

It seems to me that the kde1d package (One-Dimensional Kernel Density Estimation) is not very known. I’ve never heard of it on Stack Overflow, except in an answer of mine. However this is a ... [Read more...]

These are some of my artworks realized with the R package rgl. Source code is available in my gists. ... [Read more...]

I’m going to show how to use the DT package to do a table with child tables, and how to edit and export such a table. In order to do a table with child tables, one adds a list column to the ... [Read more...]

This blog post provides some R code for drawing focal quadrics and their curvatures lines with the rgl package. Ellipsoid The ellipsoidMesh function below generates a mesh of the ellip... [Read more...]