gfortran for R packages on ARM based machines

docker-compose.yml

# this container just serves to install the `klaR` package
# 
# usage:
# 
#   $ docker compose up -d
#   $ docker compose exec main Rscript -e "rmarkdown::render('ex7.rmd', output_format = 'pdf_document')"

services:
  main:
    container_name: main
    volumes:
      - type: bind
        source: .
        target: /workspace
    working_dir: /workspace
    ports:
      - '8888:8888'
    build:
      context: .
      dockerfile_inline: |
        FROM --platform=linux/amd64 ubuntu:20.04

        ARG DEBIAN_FRONTEND=noninteractive
        RUN apt-get clean && rm -rf /var/lib/apt/lists/* && apt-get update
        RUN apt-get install -y ca-certificates
        RUN update-ca-certificates

        # pandoc
        RUN apt-get install -y --no-install-recommends pandoc texlive-latex-base texlive-fonts-recommended
        RUN apt-get install -y --no-install-recommends texlive-latex-extra texlive-xetex texlive-lang-japanese
        RUN apt-get install -y --no-install-recommends texlive-fonts-extra texlive-lang-cjk texlive-latex-recommended texlive-bibtex-extra
        RUN apt-get install -y --no-install-recommends texlive-science texlive-pictures biber libfreetype6-dev libfontconfig1-dev

        # fortran 9
        RUN apt-get install -y gfortran-9
        RUN update-alternatives --install /usr/bin/gfortran gfortran /usr/bin/gfortran-9 100
        
        # r
        RUN apt-get clean
        RUN apt-get autoremove
        RUN apt-get update
        RUN apt-get install -y --no-install-recommends r-base r-base-dev
        RUN apt-get install -y automake build-essential zlib1g-dev r-cran-httpuv
        RUN Rscript -e 'for(p in c("rmarkdown", "ISLR", "IRkernel")) install.packages(p, repos = "https://cran.rstudio.com")'

        # klar package
        RUN Rscript -e 'install.packages("klaR", repos = "https://cran.rstudio.com")'

        CMD ["tail", "-f", "/dev/null"]

In short: the klaR package requires you to have a gfortran compiler installed.

This can be done either through the Dockerfile above or – if you're using an ARM based MacOS system, simply by installing gcc first.

brew install gcc
mkdir -p ~/.R
echo "FC = /opt/homebrew/bin/gfortran # find path via `which gfortran`
F77 = /opt/homebrew/bin/gfortran
FLIBS = -L/opt/homebrew/lib" > ~/.R/Makevars

Verify the successful installation of this package with the following command:

Sys.setenv(PATH=paste("/opt/homebrew/bin", Sys.getenv("PATH"), sep=":"))
install.packages(c("classInt", "questionr", "klaR"), type="source")

if (!requireNamespace("klaR", quietly = TRUE)) {
    stop("package klaR not found")
}