Consistent Plot Rendering and Saving Across Interactive Sessions and Reports.

sameplot

Render plots consistently across interactive R Markdown sessions, saved files, and knitr output by drawing to a ragg device and displaying the resulting image via knitr::include_graphics().

Why?

RStudio’s R Markdown inline plots, saved figures, and knitted documents can differ due to different rendering engines and sizing settings. sameplot() standardizes output by always rendering the plot to an image first and then displaying that image in the correct size.

Installation

You can install the development version from GitHub:

install.packages("pak")
pak::pak("TomNaber/sameplot")

Alternatively (remotes):

install.packages("remotes")
remotes::install_github("TomNaber/sameplot")

Usage

library(sameplot)

p <- ggplot2::ggplot(mtcars, ggplot2::aes(wt, mpg)) +
  ggplot2::geom_point() +
  ggplot2::theme_minimal()

# 1) Display a temporary PNG
sameplot(p)

# 2) Save a PNG
sameplot(p, file = file.path("figures", "mtcars.png"), save = TRUE)

# 3) Save a TIFF (still displays via a temp PNG for compatibility)
sameplot(p, file = file.path("figures", "mtcars.tiff"), save = TRUE)

Notes

• Supported output extensions for saving: .png, .tif, .tiff.

• When save = FALSE, figures are written to a temporary location and cleaned up when the R session ends.

• dpi in the knitr output is set to the same value as res used for the ragg device.

• When knitting to HTML with rmarkdown::html_document, set self_contained: true in the YAML. This ensures the images produced by sameplot() are embedded in the HTML rather than linked as external files in a temporary folder that is not accessible to the HTML when knitting is complete. Example:

  output:
    html_document:
      self_contained: true
  

sameplot() requires inline output (not “Chunk Output in Console”)

sameplot() is designed for use in .Rmd documents and works by rendering to an image file (a temporary PNG) and then displaying that file via knitr::include_graphics().

Because this returns a document output, not an interactive plot object, it does not work with Rstudio’s Chunk Output in Console mode.

To use sameplot() in RStudio, enable inline output: - Click the settings cogwheel next to the Knit button - Make sure Chunk Output Inline (not “Chunk Output in Console”) is enabled.

Optional: Matching sameplot() output without using sameplot()

Sometimes you can’t pass a plot object to sameplot(), e.g., when a function draws immediately and returns NULL. In that case you can still get device-consistent results with the settings below. Note that the solution below requires ragg to be installed with install.packages("ragg").

1) Use ragg for knitr rendering and set chunk options

Set chunk defaults either globally (setup chunk) or per-figure-containing chunk:

• dev = "ragg_png" so knitr renders using a ragg device
• fig.retina = 1 to avoid implicit upscaling
• out.width = "100%" and out.height = "100%" so the sameplot() image fills the same output box as regular chunk figures.
• Explicit fig.width, fig.height, and dpi (these example matches sameplot() defaults)

Example (setup chunk):

knitr::opts_chunk$set(
  dev = "ragg_png",
  fig.retina = 1,
  out.width = "100%",
  out.height = "100%",
  fig.width  = 6.4,
  fig.height = 4.8,
  dpi = 300
)

2) Set AGG backend in RStudio for inline output

In RStudio, set: Tools → Global Options... → General → Graphics → Backend → AGG.