Using Plotly to Visualize ShinyMatrix Input in R Shiny App: A Practical Guide

Using Plotly to Visualize ShinyMatrix Input in R Shiny App

=====================================================

In this article, we will explore how to use the plotly package to visualize the input of a shinyMatrix in an R Shiny app. We will also discuss the main issue with using a for-loop inside a reactive environment and provide a solution.

Introduction

A shinyMatrix is a type of input widget provided by the shinyMatrix package, which allows users to create matrices with interactive sliders, buttons, and other inputs. The plotly package provides an excellent way to visualize data in R Shiny apps, including mesh plots.

Main Issue

The main issue with using a for-loop inside a reactive environment is that the variable df (data frame) is not treated as a function, resulting in an error message “object of type closure is not subsettable”. This occurs because the for-loop is executed every time the input changes, creating a new data frame for each iteration.

Solution

To solve this issue, we need to use the same name for both the reactive and the data frame. We also need to return the data frame after the for-loops have finished executing.

server <- function(input, output, session) {
  # Create a new data frame to store the x, y, and z coordinates
  dd <- data.frame(x = NA, y = NA, z = NA)

  # Use reactive to create the data frame inside the loop
  df <- reactive({
    n <- 1
    for (i in 1:nrow(input$mat)) {
      for (j in 1:ncol(input$mat)) {
        dd[n, 1] <- j * laenge
        dd[n, 2] <- i * laenge
        dd[n, 3] <- input$mat[i, j]
        n <- n + 1
      }
    }
    # Return the data frame after the loops have finished
    return(dd)
  })

  # Use renderPlotly to create a plotly mesh plot from the data frame
  output$plotly <- renderPlotly({
    # Convert df to a data frame suitable for plotly
    plot_ly(df(), x = ~x, y = ~y, z = ~z, type = "mesh3d")
  })
}

Using `shinyMatrix` and Plotly

To use shinyMatrix with plotly, we need to create a new ui in our Shiny app that includes the matrixInput widget.

# Create a new UI for the Shiny app
ui <- fluidPage(
  # Add a title panel to the app
  titlePanel("ShinyMatrix: Simple App"),
  
  # Add a sidebar panel with interactive sliders and buttons
  sidebarPanel(width = 6, tags$h4("Data"), 
                matrixInput("mat", 
                            value = matrix(1:100, 10, 10), 
                            rows = list(names=T, extend = TRUE), 
                            cols = list(names = TRUE))),
  
  # Add a main panel to display the plotly mesh plot
  mainPanel(width = 6,
            plotlyOutput(
              "plotly",
              width = "100%",
              height = "400px",
              inline = FALSE,
              reportTheme = TRUE
            ))
)

Example Use Case

To use shinyMatrix with plotly, we can create a new R Shiny app that includes the above code.

# Create a new shiny app that uses matrixInput and plotly
library(shiny)

# Define the UI for the app
ui <- fluidPage(
  titlePanel("ShinyMatrix: Simple App"),
  
  # Add a sidebar panel with interactive sliders and buttons
  sidebarPanel(width = 6, tags$h4("Data"), 
                matrixInput("mat", 
                            value = matrix(1:100, 10, 10), 
                            rows = list(names=T, extend = TRUE), 
                            cols = list(names = TRUE))),
  
  # Add a main panel to display the plotly mesh plot
  mainPanel(width = 6,
            plotlyOutput(
              "plotly",
              width = "100%",
              height = "400px",
              inline = FALSE,
              reportTheme = TRUE
            ))
)

# Define the server-side logic for the app
server <- function(input, output, session) {
  # Use reactive to create the data frame inside the loop
  dd <- data.frame(x = NA, y = NA, z = NA)

  df <- reactive({
    n <- 1
    for (i in 1:nrow(input$mat)) {
      for (j in 1:ncol(input$mat)) {
        dd[n, 1] <- j * laenge
        dd[n, 2] <- i * laenge
        dd[n, 3] <- input$mat[i, j]
        n <- n + 1
      }
    }
    return(dd)
  })

  # Use renderPlotly to create a plotly mesh plot from the data frame
  output$plotly <- renderPlotly({
    plot_ly(df(), x = ~x, y = ~y, z = ~z, type = "mesh3d")
  })
}

# Run the app
shinyApp(ui = ui, server = server)

Conclusion

In this article, we explored how to use plotly to visualize the input of a shinyMatrix in an R Shiny app. We discussed the main issue with using a for-loop inside a reactive environment and provided a solution.

Last modified on 2023-07-28