How to display flowchart created using R Diagram library in an Rshiny app?

Question

I am trying to display a flowchart using R Diagram Library in an RShiny app similar to that one shown below. I tried plotOutput() but was not able to display the flowchart in the Rshiny app tab. Can someone please enlighten me on what am I missing here?

library(diagram)
library(shape)

    par(mar = c(1, 1, 1, 1))
    openplotmat()
    elpos <- coordinates (c(1, 1, 2, 4))
    fromto <- matrix(ncol = 2, byrow = TRUE, data = c(1, 2, 2, 3, 2, 4, 4, 7, 4, 8,3,5,3,6))
    nr <- nrow(fromto)
    arrpos <- matrix(ncol = 2, nrow = nr)
    for (i in 1:nr)
      arrpos[i, ] <- straightarrow (to = elpos[fromto[i, 2], ],
                                      from = elpos[fromto[i, 1], ], lwd = 2, arr.pos = 0.6, arr.length = 0.5)
      textellipse(elpos[1,], 0.1, lab = "start", box.col = "green",
                  shadow.col = "darkgreen", shadow.size = 0.005, cex = 1.5)
      textrect (elpos[2,], 0.15, 0.05,lab = "found term?", box.col = "grey",
                  shadow.col = "darkblue", shadow.size = 0.005, cex = 1.5)
      textrect (elpos[4,], 0.15, 0.05,lab = "related?", box.col = "grey",
                  shadow.col = "darkblue", shadow.size = 0.005, cex = 1.5)
      textellipse(elpos[3,], 0.1, 0.1, lab = c("other","term"), box.col = "orange",
                    shadow.col = "red", shadow.size = 0.005, cex = 1.5)
      textellipse(elpos[7,], 0.1, 0.1, lab = c("make","a link"),box.col = "orange",
                    shadow.col = "red", shadow.size = 0.005, cex = 1.5)
      textellipse(elpos[8,], 0.1, 0.1, lab = c("new","article"),box.col = "orange",
                    shadow.col = "red", shadow.size = 0.005, cex = 1.5)
      textellipse(elpos[5,], 0.1, 0.1, lab = c("make","a link"),box.col = "orange",
                  shadow.col = "red", shadow.size = 0.005, cex = 1.5)
      textellipse(elpos[6,], 0.1, 0.1, lab = c("new","article"),box.col = "orange",
                  shadow.col = "red", shadow.size = 0.005, cex = 1.5)
    #
     dd <- c(0.0, 0.025)
      text(arrpos[2, 1] + 0.05, arrpos[2, 2], "yes")
      text(arrpos[3, 1] - 0.05, arrpos[3, 2], "no")
      text(arrpos[4, 1] + 0.05, arrpos[4, 2] + 0.05, "yes")
      text(arrpos[5, 1] - 0.05, arrpos[5, 2] + 0.05, "no")
    #

Answer 1

Did you also use plotOutput in the ui, and renderPlot in the server? I tried the following, and it works for me.

# This is a Shiny web application. You can run the application by clicking
# the 'Run App' button above.
#
# Find out more about building applications with Shiny here:
#
#    http://shiny.rstudio.com/
#

library(shiny)
library(diagram)
library(shape)

# Define UI for application that draws a histogram
ui <- fluidPage(
  # Show a plot of the generated distribution
  mainPanel(
    plotOutput("testplot")
  )
)

# Define server logic required to draw a histogram
server <- function(input, output) {
  #
  output$testplot <- renderPlot({
    par(mar = c(1, 1, 1, 1))
    openplotmat()
    elpos <- coordinates (c(1, 1, 2, 4))
    fromto <- matrix(ncol = 2, byrow = TRUE, data = c(1, 2, 2, 3, 2, 4, 4, 7, 4, 8,3,5,3,6))
    nr <- nrow(fromto)
    arrpos <- matrix(ncol = 2, nrow = nr)
    for (i in 1:nr)
      arrpos[i, ] <- straightarrow (to = elpos[fromto[i, 2], ],
                                    from = elpos[fromto[i, 1], ], lwd = 2, arr.pos = 0.6, arr.length = 0.5)
    textellipse(elpos[1,], 0.1, lab = "start", box.col = "green",
                shadow.col = "darkgreen", shadow.size = 0.005, cex = 1.5)
    textrect (elpos[2,], 0.15, 0.05,lab = "found term?", box.col = "grey",
              shadow.col = "darkblue", shadow.size = 0.005, cex = 1.5)
    textrect (elpos[4,], 0.15, 0.05,lab = "related?", box.col = "grey",
              shadow.col = "darkblue", shadow.size = 0.005, cex = 1.5)
    textellipse(elpos[3,], 0.1, 0.1, lab = c("other","term"), box.col = "orange",
                shadow.col = "red", shadow.size = 0.005, cex = 1.5)
    textellipse(elpos[7,], 0.1, 0.1, lab = c("make","a link"),box.col = "orange",
                shadow.col = "red", shadow.size = 0.005, cex = 1.5)
    textellipse(elpos[8,], 0.1, 0.1, lab = c("new","article"),box.col = "orange",
                shadow.col = "red", shadow.size = 0.005, cex = 1.5)
    textellipse(elpos[5,], 0.1, 0.1, lab = c("make","a link"),box.col = "orange",
                shadow.col = "red", shadow.size = 0.005, cex = 1.5)
    textellipse(elpos[6,], 0.1, 0.1, lab = c("new","article"),box.col = "orange",
                shadow.col = "red", shadow.size = 0.005, cex = 1.5)
    #
    dd <- c(0.0, 0.025)
    text(arrpos[2, 1] + 0.05, arrpos[2, 2], "yes")
    text(arrpos[3, 1] - 0.05, arrpos[3, 2], "no")
    text(arrpos[4, 1] + 0.05, arrpos[4, 2] + 0.05, "yes")
    text(arrpos[5, 1] - 0.05, arrpos[5, 2] + 0.05, "no")
  })
}

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