Apple’s Developer Tools Unix toolchain. Install directly with xcode-select --install, or just try to use e.g. git from the terminal and have OS X prompt you to install the tools.
Homebrew package manager. A convenient way to install several of the tools here, including Emacs and Pandoc.
knitr. Reproducible plain-text documents from within R.
Python and SciPy. Python is a general-purpose programming language increasingly used in data manipulation and analysis.
RStudio. An IDE for R. The most straightforward way to get into using R and RMarkdown.
TeX and LaTeX. A typesetting and document preparation system. You can write files in .tex format directly, or you can just have it available in the background for other tools to use. The MacTeX Distribution is the one to install for OS X.
Pandoc. Converts plain-text documents to and from a wide variety of formats. Can be installed with Homebrew. Be sure to also install pandoc-citeproc for processing citations and bibliographies, and pandoc-crossref for producing cross-references and labels.
Git. Version control system. Installs with Apple’s Developer Tools, or get the latest version via Homebrew.
GNU Make. You tell make what the steps are to create the pieces of a document or program. As you edit and change the various pieces, it automatically figures out which pieces need to be updated and recompiled, and issues the commands to do that. See Karl Broman’s Minimal Make for a short introduction. Make will be installed automatically with Apple’s developer tools.
lintr and flycheck. Tools that nudge you to write neater code.
Pandoc Templates. LaTeX and HTML templates, together with Pandoc configuration files and other things needed to produce good-looking PDF, HTML, and Word documents from plain text sources using Pandoc.
md-starter project and rmd-starter project. Assuming you have the tools and Pandoc/LaTeX templates installed, these skeleton project folders contain a basic .md or .rmd starter file and a Makefile to produce .html, .tex, .pdf and .docx files as described in this guide.
RStudio Cheatsheets Other quick guides, including a more comprehensive RMarkdown reference and a information about using RStudio’s IDE, and some of the main tools in R.
Jenny Bryan’s Stat 545. Notes and tutorials for a Data Analysis course taught by Jennifer Bryan at the University of British Columbia. Lots of useful material.
knitr demos Documentation and examples for knitr by its author, Yihui Xie. There is also a knitr book covering the same ground in more detail.
GitHub. Host public Git repositories for free. Pay to host private ones. Also a source for publicly available code (e.g. R packages and utilities) written by other people.
Marked 2. Live HTML previewing of Markdown documents. Mac OS X only.
Zotero, Mendeley, and Papers are citation managers that incorporate PDF storage, annotation and other features. Zotero is free to use. Mendeley has a premium tier. Papers is a paid application after a trial period. I don’t use these tools much, but that’s not for any strong principled reason—mostly just intertia. If you use one and want to integrate with the material here, just make sure it can export to BibTeX/BibLaTeX files. Papers, which I’ve used most recently, can handily output citation keys in pandoc’s format amongst several others.