One file, two formats

Quarto parameters, interactive HTML and PowerPoint

Start here

Goal: write one Quarto file, render HTML and PowerPoint, and switch a plot on or off.

A parameter is a named setting you choose when rendering. Here, show_plot controls whether a plot appears.

You need Quarto, R, and the R packages knitr, rmarkdown, and plotly installed. The plot uses R’s built-in cars dataset.

If needed, install the packages once in the R console, before rendering:

install.packages(c("knitr", "rmarkdown", "plotly"))

In Positron, create a plain text file named my-report.qmd. Use the Source editor to enter the code in steps 1 and 2.

1. Add the header

Put this at the very top of my-report.qmd, including both --- lines:

---
title: "My first parameterized report"
format:
  html:
    embed-resources: true
  pptx: default
params:
  show_plot: true
execute:
  echo: false
---

Keep the indentation. true shows the plot; false hides it. Embedded resources make the HTML easy to share as one file.

2. Add the content

Below the header, add this text and R chunk, including the backticks:

## My plot

Stopping distance and speed from R's cars dataset.

```{r}
if (params$show_plot) {
  if (knitr::is_html_output()) {
    p <- plotly::plot_ly(cars, x = ~speed, y = ~dist,
                         type = "scatter", mode = "markers")
    plotly::layout(p,
                   xaxis = list(title = "Speed (mph)"),
                   yaxis = list(title = "Stopping distance (ft)"))
  } else {
    plot(cars$speed, cars$dist,
         xlab = "Speed (mph)",
         ylab = "Stopping distance (ft)",
         pch = 19)
  }
}
```

params$show_plot reads the setting. if (...) runs the plotting code only when it is true. echo: false hides the code in the output.

knitr::is_html_output() checks the output format. For HTML, it creates an interactive Plotly plot. For PowerPoint, the else branch draws the same data with R’s plot(), which Quarto inserts as a static image.

3. Render both formats

Save the file. Open Positron’s Terminal in the folder containing my-report.qmd and run these commands one at a time:

quarto render my-report.qmd --to html
quarto render my-report.qmd --to pptx

Open my-report.html in a browser: hover over points to see their values and drag to zoom. Double-click the plot to reset the view.

Open my-report.pptx in PowerPoint: the plot is a regular image, with no hover or zoom controls.

The same ## heading becomes a section in HTML and a slide heading in PowerPoint. Run these commands in the Terminal, not the R console.

4. Hide the plot

In the header, change show_plot: true to show_plot: false. Save and rerun both commands. Reopen the outputs: the text stays, but the plot disappears.

You can also override the setting for one render without editing the file:

quarto render my-report.qmd --to html -P show_plot:true
quarto render my-report.qmd --to pptx -P show_plot:true

These commands bring the plot back, even with false saved in the header. Each render replaces the corresponding output file.

Done when: you have opened both formats and seen each with and without the plot.

Keep handy

• Define the setting under params: in the header.
• Read it in R with params$show_plot.
• Choose the format with --to html or --to pptx.
• Use knitr::is_html_output() to choose an interactive or static plot.
• Override the setting with -P show_plot:false.

References: Quarto’s parameter guide and Plotly scatter plots.