How do I display text output in Shiny depending on the result of a caluclation?-CodePudding

I am using Shiny and have three goals:

a) user is able to select variables from a drop down menu

b) Cramer's V is calculated and the result is displayed on the screen

c) Depending on the result, a particular text output is displayed eg "this is a strong association"

I have successfully been able to complete goal a and b. I have tried various attempts at goal three but to no avail.

This one block of code below shows two attempts that do not work:

library(shinydashboard)
library(shiny)
library(dplyr)
library(DT)
library(rcompanion)

df <- data.frame(ACCIDENT_MASTER_single)

Cat1.Variables <- c("SEVERITY", "ATMOSPH_COND", "DAY_OF_WEEK", "CAT")
Cat2.Variables <- c("SEVERITY", "ATMOSPH_COND", "DAY_OF_WEEK", "CAT")

ui <- fluidPage(
  titlePanel("Calculate the strength of the relationship between categorical variables"),
  sidebarLayout(
    
    sidebarPanel(
      selectInput("cat1", choices = Cat1.Variables, label = "Select a Categorical Variable:"),
      selectInput("cat2", choices = Cat2.Variables, label = "Select a Categorical Variable:")
    ),
    
    mainPanel(
      textOutput("text1"),
      h3(tableOutput("results")),
      textOutput("text2")
    )
  )
)


server <- shinyServer(function(input, output) {
  
  cramerdata <- reactive({
    req(input$cat1, input$cat2)
    df3 <- data.matrix(ACCIDENT_MASTER_single[c(input$cat1, input$cat2)])
    df3
  })
  
  results <- reactive({
    cramerV(cramerdata())
  })
  
  output$text1 <- renderText({ 
    paste("You have selected variables:", input$cat1, input$cat2) 
  })
  
  output$results <- renderPrint({
    cat(sprintf("\nThe results equal: \n"))
    x <- cramerV(cramerdata())
    print(x)
    
    if (x >.5) {
      return(paste("<span style=\"color:red\">There is a strong association between the selected variables </span>"))
    } else if
    (x > 0.3 && x <= 0.5) {
      "There is a medium association between the selected variables"
    } else if
    (x > 0.1 && x <= 0.3) {
      "There is a weak association between the selected variables"
    } else
      "There is a very weak association between the selected variables"
    
  })
  
    output$text2 <- renderText({ 
      
   
      if (x >.5) {
        return(paste("<span style=\"color:red\">There is a strong association between the selected variables </span>"))
      } else if
      (x > 0.3 && x <= 0.5) {
        "There is a medium association between the selected variables"
      } else if
      (x > 0.1 && x <= 0.3) {
        "There is a weak association between the selected variables"
      } else
        "There is a very weak association between the selected variables"

  })
})
shinyApp(ui, server)

The output I get under output$results are as follows:

The results equal: Cramer V 0.605 [1] "There is a strong association between the selected variables "

I understand the output looks like this with the [1] and the "" because I am using renderPrint. However, when I use renderText I get the text output producing the correct output but the result of Cramer's V is not displayed at all (goal b).

You can see in my code I have also tried to put the text output separately under output$text2 but it produces this result:

Error: object 'x' not found.

Can anyone please help solve this problem?

Thanks

CodePudding user response：

Your second attempt is not working because variable 'x' is not global, it's defined under output$results and you can't access it in output$text2. I cannot run your whole code since you didn't provide the necessary data but I guess this would do the job for you:

# in the ui change your tableOutput() to textOutput() for 'results':

    h3(textOutput("results"))

# in the server change your output$results to this:

output$results <- renderText({
    x <- cramerV(cramerdata())
    print(paste("The results equal:", x, ifelse(x > 0.5, "There is a strong association between the selected variables",
                                                ifelse(x > 0.3 && x <= 0.5, "There is a medium association between the selected variables",
                                                       ifelse(x > 0.1 && x <= 0.3, "There is a weak association between the selected variables", "There is a very weak association between the selected variables")))))
  })

P.S. You had already put cramerV(cramerdata()) under the results() reactive element, so why are you not using that under the output$results.
P.S.S: try not to use the same name for variables and functions (like results here both as reactive element and output)