tikz_fun.Rmd

---
title: "Fancy math"
output:
  html_document: default
  pdf_document: default
---

```{r setup, include=FALSE}
# Conditional tikz output types; use PDF if this is LaTeX, otherwise use a
# shrunken down high resolution PNG
if (knitr::is_latex_output()) {
  knitr::opts_template$set(
    tikz.output = list(fig.ext = "pdf")
  )
} else {
  knitr::opts_chunk$set(dev.args = list(type = "cairo"))
  
  knitr::opts_template$set(
    tikz.output = list(fig.ext = "png", out.width = "45%", dpi = 300)
  )
}
```

Here's some tikz stuff in an R Markdown file. It works in HTML, Word, and LaTeX/PDF!

```{r eval=FALSE, include=FALSE}
# Via https://github.com/ilundberg/slides/blob/master/what_is_your_estimand/what_is_your_estimand_equations.tex
```

```{tikz, testing-stuff, cache=TRUE, echo=FALSE, fig.align="center", opts.label = "tikz.output"}
\begin{tikzpicture}[x = .85cm, y = .85cm]
    \node at (0,0) {$\tau = \frac{1}{n}\sum_{i=1}^n
    \bigg(
        Y_i\left(\substack{\text{White,}\\\text{Record}}\right) 
        - 
        Y_i\left(\substack{\text{Black,}\\\text{No record}}\right)
    \bigg)$};
    \node[anchor = north, font = \scriptsize, align = center] at (-2.6,-1) {Mean\\over \textbf{all}\\applications};
    \node[anchor = north, font = \scriptsize, align = center] at (-.1,-1) {Potential\\outcome under\\one condition};
    \node[anchor = north, font = \scriptsize, align = center] at (2.5,-1) {Potential\\outcome under\\another condition};
    \draw[->, thick] (-2.5,-1) -- (-2.2,-.5);
    \draw[->, thick] (0,-1) -- (0,-.5);
    \draw[->, thick] (2.5,-1) -- (2.2,-.5);
\end{tikzpicture}
```

And here's some fancypants math with under and over braces. It also works both in HTML and PDF:

$$
\underbrace{\hat{y}_{it}}_{\substack{\text{Outcome} \\ \\ i = \text{individual} \\ t = \text{time period}}} = \overbrace{\alpha_{it}}^{\text{Intercept}} + \overbrace{\beta x_{it}}^{\substack{\text{Treatment} \\ \text{coefficient}}}
$$