CODEWITHSUNDEEP
rshinyshinyjs
Gabriel
Gabriel

Reputation: 425

use pre assigned variable inside R shiny function as a parameter

I am creating a survey using R shiny and have the following function at the beginning of my Shiny App:

install.packages("devtools")
spotifydata<-spotifycharts::chart_top200_weekly()
s<-spotifydata$artist
h<-head(s,20)

I want to know if there is anywhere to display the output of variable "h"??

I had the idea of using "selectInput" in the following manner to display each result in a drop down menu fashion.

 selectInput("artists","pick 3 artists out of the top 10",
              c("h[1]","h[2]","h[3]","h[4]","h[5]","h[6]",
                "h[7]","h[8]","h[9]","h[10]"),multiple = TRUE)

I know this produces an error But I want to know if there is a way to emulate this

Upvotes: 1

Views: 58

Answers (1)

SBista
SBista

Reputation: 7694

In the selectInput the variables should be written without quotes like this:

 selectInput("artists","pick 3 artists out of the top 10",
                c(h[1],h[2],h[3],h[4],h[5],h[6],
                  h[7],h[8],h[9],h[10]),multiple = TRUE)

Following is an app showing the working of the same:

library(shiny)

spotifydata<-spotifycharts::chart_top200_weekly()
s<-spotifydata$artist
h<-head(s,20)

ui <- fluidPage(
    selectInput("artists","pick 3 artists out of the top 10",
                c(h[1],h[2],h[3],h[4],h[5],h[6],
                  h[7],h[8],h[9],h[10]),multiple = TRUE)
)

server <- function(input, output)
{}

shinyApp(ui, server)

The output is as follows:

enter image description here

Please note that with this approach the variable h is shared between different user sessions.

If you don't want the variable h to be shared between different user sessions you can use the following approach, where we get h value within the server function and update the choices of select input using the function updateSelectInput 

ui <- fluidPage(
  selectInput("artists","pick 3 artists out of the top 10",
              choices = c(), multiple = TRUE)
)

server <- function(input, output, session)
{
  observe({

    spotifydata<-spotifycharts::chart_top200_weekly()
    s<-spotifydata$artist
    h<-head(s,20)

    updateSelectInput(session, inputId = "artists", choices = c(h[1],h[2],h[3],h[4],h[5],h[6],
                                                                h[7],h[8],h[9],h[10]))

  })

}

shinyApp(ui, server)

Upvotes: 1

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