How to make this R Shiny table example reactive? - r

Question

I found the following code that creates an RShiny app that allows users to visualize a data table based on certain columns that they select. See following code (should run on it's own):
library(shiny)
library(ggplot2) # for the diamonds dataset
ui <- fluidPage(
title = "Examples of DataTables",
sidebarLayout(
sidebarPanel(
conditionalPanel(
'input.dataset === "diamonds"',
checkboxGroupInput("show_vars", "Columns in diamonds to show:",
names(diamonds), selected = names(diamonds))
)
),
mainPanel(
tabsetPanel(
id = 'dataset',
tabPanel("diamonds", DT::dataTableOutput("mytable1")),
)
)
)
)
server <- function(input, output) {
# choose columns to display
diamonds2 = diamonds[sample(nrow(diamonds), 1000), ]
output$mytable1 <- DT::renderDataTable({
DT::datatable(diamonds2[, input$show_vars, drop = FALSE])
})
}
shinyApp(ui, server)
My question is, how can I change this dataset to be reactive, such that instead of always using the diamonds dataset, a data table would result based on what dataset I select from a dropdown menu? Such as adding a selectInput() argument?

Answer 1

If you are just trying to have different tables show based on a selectInput(), then this will work for a small number of tables. Essentially, the output table is an if else statement, which displays a different table depending on what's selected in the selectInput().
library(shiny)
library(ggplot2) # for the diamonds dataset
ui <- fluidPage(
title = "Examples of DataTables",
sidebarLayout(
sidebarPanel(
selectInput("Datasetchoice", "Dataset", choices = c("diamonds", "iris", "mtcars")), #Choose which dataset to display
conditionalPanel(
'input.dataset === "diamonds"',
checkboxGroupInput("show_vars", "Columns in diamonds to show:",
names(diamonds), selected = names(diamonds))
)
),
mainPanel(
tabsetPanel(
id = 'dataset',
tabPanel("diamonds", DT::dataTableOutput("mytable1"))
)
)
)
)
server <- function(input, output) {
# choose columns to display
diamonds2 = diamonds[sample(nrow(diamonds), 1000), ]
output$mytable1 <- DT::renderDataTable({
if(input$Datasetchoice == "diamonds") { #If else statement, show a different table depending on the choice
DT::datatable(diamonds2[, input$show_vars, drop = FALSE])
} else if (input$Datasetchoice == "iris") {
DT::datatable(iris)
} else if(input$Datasetchoice == "mtcars") {
DT::datatable(mtcars)
}
})
}
shinyApp(ui, server)

Answer 2

Here is a solution that updates the checkboxes and the table upon selection of a different dataset. No limit on the number of datasets. But the datasets must be dataframes.
library(shiny)
library(datasets) # for the datasets
ui <- fluidPage(
title = "Examples of DataTables",
sidebarLayout(
sidebarPanel(
selectInput("dat",
label = "Choose data",
choices = c("cars", "mtcars", "faithful", "iris", "esoph", "USArrests")),
checkboxGroupInput("datavars", "Columns to show",
choices = NULL,
selected = NULL)
),
mainPanel(
tabsetPanel(
id = 'dataset',
tabPanel("dataset", DT::dataTableOutput("mytable1")),
)
)
)
)
server <- function(input, output, session) {
r <- reactiveValues(
dataobj = NULL
)
observeEvent(input$dat, {
dataobj <- r$dataobj <- get(input$dat, 'package:datasets')
datavars <- names(dataobj)
freezeReactiveValue(input, "datavars")
updateCheckboxGroupInput(session, "datavars",
choices = datavars,
selected = datavars)
})
output$mytable1 <- DT::renderDataTable({
req(r$dataobj, input$datavars)
DT::datatable(r$dataobj[, input$datavars, drop = FALSE])
})
}
shinyApp(ui, server)