R Shiny : dynamic number of tables within a tab - r

Question

first I know there is a lot of threads covering my problem, I read them all, but I did not manage to do it. I got a list of 10 data.frame which I built through the following code :
list_of_df=list()
for (i in seq(1,10)){
number_row=sample(seq(5,10),size = 1)
num=seq(1,number_row)
val=sample(x = letters,size = number_row,replace = TRUE )
df=data.frame(num=num,
val=val)
rownames(df)=NULL
list_of_df[[i]]=df
}
I want the user to enter n, the number of tables he wants to see. And then display n random tables from the list_of_df. I want to display those tables inside tabs. Here is what I did, I grabbed some ideas here and there, but obviously it does not work and I do not know why.
library(shiny)
# ui function
ui = pageWithSidebar(
headerPanel('Dynamic Tabs'),
sidebarPanel(
numericInput(inputId = "numput",label = "number of tables",value = 1,min = 1,max = 5)
),
mainPanel(
uiOutput('mytabs')
)
)
# server function
server = function(input, output, session){
random_tables<- reactive({
index=sample(seq(1,10),size = input$numput,replace=FALSE)
list_of_df[[index]]
})
size<-reactive({
length(random_tables())
})
for (i in 1:size()) {
local({
my_i <- i
tablename <- paste("table_", my_i, sep="")
output[[tablename]] <- renderTable({
random_tables()[[i]]
})
})
}
output$mytabs = renderUI({
nTabs = size()
myTabs = lapply(paste0('table_', 1: nTabs), function(x){
tabPanel(x, tableOutput(x))
})
do.call(tabsetPanel, myTabs)
})
}
shinyApp(ui, server)
So, if you see what I should do ...

Answer 1

Here is a working version:
library(shiny)
# ui function
ui = pageWithSidebar(
headerPanel('Dynamic Tabs'),
sidebarPanel(
numericInput(inputId = 'numput',label = "number of tables",value = 1,min = 1,max = 5)
),
mainPanel(
uiOutput('mytabs')
)
)
# server function
server = function(input, output, session){
list_of_df=list()
for (i in seq(1,10)){
number_row=sample(seq(5,10),size = 1)
num=seq(1,number_row)
val=sample(x = letters,size = number_row,replace = TRUE )
df=data.frame(num=num,
val=val)
rownames(df)=NULL
list_of_df[[i]]=df
}
random_tables<- reactive({
index=sample(seq(1,10),size = input$numput,replace=FALSE)
list_of_df[index]
})
size<-reactive({
input$numput
})
observe({
lapply(seq_len(size()), function(i) {
local({
my_i <- i
tablename <- paste("table_", my_i, sep="")
output[[tablename]] <- renderTable({
random_tables()[[i]]
})
})
})
})
output$mytabs = renderUI({
nTabs = size()
myTabs = lapply(paste0('table_', seq_len(nTabs)), function(x){
tabPanel(x, tableOutput(x))
})
do.call(tabsetPanel, myTabs)
})
}
shinyApp(ui=ui,server=server)
A couple issues, you subset the list with double brackets, but it isn't working like you think it is, you need single brackets. Next when you select a single table random_table() is a data.frame so when you call length you get 2, the number of columns. So just use the input$numput for size() since they are the same anyways. Also, I put the dynamic output in an observe so that it can access the reactive size(). A small thing, but I used seq_len instead of 1:aNumber since it is more robust.
Hope this helps