R Shiny：根据从 selectInput 中选择的问题动态显示文本

Question

I am building a Shiny app, and want the app to display an answer text from a Q&A list stored as a csv file based on what question the user choose in a drop down list. I am new to Shiny so would be really grateful for beginner explanation and example code.

I have stored a list in a csv-file which contains a list of questions and answers.

So, this is what I need the app to do:

First, the user will choose an option in a drop down list I have created with selectInput.

Second, I want the app to display a paragraph of text, based on the choice that the user has made. The text to be displayed is stored in the csv file, which contains basically two columns: all the different choices/questions in columnA, and the corresponding answer in the second column, columnB.

So the app needs to find the correct answer to be displayed based on the question that the user chooses from the choices in the selectInput.

How do you achieve this?

Many thanks in advance!

Answer 1

You are able to do this with the code below. You'll need remove the hard-coded answers data I've put in and uncomment the line that reads the answers from csv . Similarly for the question choices.

library(shiny)

# answers <- read.csv('path/to/file')
question_choices <- c('question 1', 'question 2')
# question_choices <- answers$q

ui <- fluidPage(
  selectInput(
    'question',
    'Select Question:',
    choices = question_choices
  ),
  textOutput('answer')
)

server <- function(input, output, session) {
  answers <- tribble(
    ~q, ~a,
    'question 1', 'answer 1',
    'question 2', 'answer 2'
  )
  
  output$answer <- renderText({
    answers[answers$q == input$question, ]$a
  })
}

shinyApp(ui, server)