In tomicapretto/shinymath: Mathematical Input for Shiny Apps

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "man/figures/README-",
  out.width = "100%"
)

shinymath

shinymath is a small R package that provides a mathematical input to shiny apps. This input is based on Mathquill and by default returns a LaTeX expression. This package also uses functions from latex2r that make it possible to transform the LaTeX expressions to R code/functions.

Installation

You can install the development version from GitHub with:

# install.packages("remotes")
remotes::install_github("tomicapretto/shinymath")

Basic usage

Within your UI, you call mathInput() as you would do with any other input.

mathInput(inputId = "equation", label = "Math equation")

Examples

Quickstart

Just a quick example to see mathInput() together with latex2r() in action.

library(shiny)
library(shinymath)

ui = fluidPage(
  title = "Hello shinymath!",
  mathInput("math", "Equation"),
  actionButton("go", "Go!"),
  h4("Raw text"),
  verbatimTextOutput("text_raw", placeholder = TRUE),
  h4("Translation to R code"),
  verbatimTextOutput("text_r", placeholder = TRUE)
)

server = function(input, output) {
  math = eventReactive(input$go, input$math)
  output$text_raw = renderText(math())
  output$text_r = renderText(latex2r(math()))
}

shinyApp(ui, server)

All features demo

The app has a small shiny app that shows the features related to mathInput() and functions exported from latex2r package. Use launch_demo() to see it.

Notes

While you can write any math that is accepted by Mathquill, not everything can be translated to R. Since this package relies on the parser in latex2r for translation purposes, it comes with all the limitations there. For more information about the particularities of latex2r, see these notes.

However, many common mathematical equations can be written and translated to R code with no problem. Here you have a list of math equations in LaTeX and their corresponding translation to R.

A good choice is to wrap latex2r() call within a tryCatch() block to handle parsing errors in a custom way. When the parser does not understand the math expression, it raises an error of class latex2r.error. Within your shiny app, you can use something like

latex2r_safe = function(code) {
  tryCatch({
    latex2r(code)
  },
  latex2r.error = function(cnd) {
    showNotification(
      paste("Error when translating to R code -", cnd$message),
      type = "error"
    )
  },
  error = function(cnd) {
    showNotification("Unexpected error", type = "error")
  })
}