How to create quick and dirty beamer animations with rmarkdown and knitr

beamer-overlay.Rmd

---
title: 'Beamer Overlay Test'
output:
  beamer_presentation:
    incremental: true
    theme: CambridgeUS
---


```{r, echo = FALSE}
hook_plot <- knitr::knit_hooks$get("plot")
knitr::knit_hooks$set(
  plot = function(x, options) {
    if (is.null(options$overlay.plot)) {
      return(hook_plot(x, options))
    } else {
      i <- options$fig.cur
      hand <- as.numeric(ifelse(i == options$overlay.plot, 1, 0))
      bf <- paste0("\\only<", i, "| handout:", hand, ">{")
      paste(c(bf, knitr::hook_plot_tex(x, options), "}"), collapse = "\n")
    }
  }
)
```


## Frame title

```{r fig, fig.width = 10, fig.height = 7, out.width = "\\textwidth", echo = FALSE, overlay.plot = 1}
set.seed(12345)
x1 <- runif(100)
y1 <- rnorm(100)
cuts <- c(0, 0.25, 0.5, 0.75, 1)
for (i in seq_along(cuts)) {
  cols <- ifelse(x1 <= cuts[i], "indianred", "grey80")
  plot(x1, y1, col = cols, pch = 19)
  abline(v = cuts[i], lwd = 3, col = "indianred")
}
```