[R] Use trelliscopejs to arrange plots

Trelliscope is an R package which interfacing a Javascript library trelliscopejs. This library provides an visulization of data by splitting them into subsets, also called ‘Trellis Display’ or “small multiples”.

The R package provides some high-level functions such as facet_trelliscope() which can directly replace the function ggplot2::facet_wrap() when making plots. The advantage of the former is that it can create multiple pages of plots when there are many, but facet_wrap() will put them into one plot. Also the trelliscope plot is an interactive htmlwidget, so users can sort, filter, and arrange the plots.

Let’s start with a demo.

facet_trelliscope

Here we use the function facet_trelliscope() to wrap around plots based on the data in mtcars.

library(trelliscopejs)

## Warning: package 'trelliscopejs' was built under R version 4.0.5

library(ggplot2)

## Warning: package 'ggplot2' was built under R version 4.0.5

library(htmltools)

## Warning: package 'htmltools' was built under R version 4.0.4

ggplot(data=mtcars, aes(x=wt,y=mpg)) + geom_point() +
  facet_trelliscope(~am + gear, nrow=1, ncol = 2,
                    name="Test trelliscope", desc="This is desc",
                    self_contained = F, path=".",
                    as_plotly = F)

## using data from the first layer

tags$iframe(src="/trelliscope_out/index.html", width="100%", height="400px")

Unfortunately, this plot doesn’t work at present in blogdown deploy, even after upgrading all R packages and hugo. Will look into this later. As a temporary solution, I generated this plot into a file and saved it into static/trelliscope_out/index.html along with its dependencies, and then embed this file using iframe as above.

As you can see, the usage is pretty straightforward. In the trelliscope panel, one can change the grid and sort the plots based on precomputed metrics. Here we have only 4 plots, so its power to organize many plots is not well demonstrated, but the principle is the same.

Notes on the arguments of facet_trelliscope():

~am + gear: the formula to facet the panels. Check ggplot2::facet_wrap() for more details.
nrow and ncol: the number of rows and columns for the panel grid to initally display.
name and desc: the main title and description for the trellis display.
self_contained: set to TRUE when to include all the plots in the output html file; otherwise a folder ‘appfiles’ is produced to store the plots and is needed when browsing the output html file. However, if the plots are plotly format (when argument as_plotly is TRUE), this argument can’t be ‘TRUE’ because this would not work.
path: this is the base directory for the trelliscope display to work; basically it relies on this to find ‘appfiles’ folder. This must be set to ‘.’ when trelliscope display is embedded in Rmarkdown file, just like here.
as_plotly: make plots as interactive plotly objects.

This function also have many other arguments, which can be checked from its help page.

References

Introduction to trelliscopejs: https://cran.r-project.org/web/packages/trelliscopejs/vignettes/trelliscopejs.html

Last modified on 2021-08-12