Shiny assign reactive variable from input using loop - loops

Question

I'm trying to assign reactive variable based on my input using loop. For example, I want to select the column (from input) in iris data set. Then get the unique value from that column. And I want to do this in the loop. I find it works for my 'joke' variable, but not for my 'Group[[paste0('Gcol',i)]]' variable. I've been searching answer for this for days.
Thank you for your help in advance!
library(shiny)
data=iris
ui <- fluidPage(
titlePanel("Old Faithful Geyser Data"),
sidebarLayout(
sidebarPanel(
fluidRow(
column(9,wellPanel(lapply(1:5, function(i) {
selectizeInput(paste0('GroupVar',i), paste0('Group ',i), choices = sort(colnames(data)),
options = list(placeholder = 'Select one',
onInitialize = I('function() {
this.setValue(""); }')))
})
)))
),
mainPanel(
fluidRow(column(6, wellPanel(
lapply(1:5, function(i) {
uiOutput(paste0('GroupOpt', i))
})
))),
textOutput("try4"),
textOutput("try2"),
textOutput("try21"),
textOutput("try3"),
textOutput("try")
)
)
)
server <- function(input, output) {
Group=reactiveValues()
for (i in 1:5){
Group[[paste0('Gcol',i)]]=reactive({
data[,which(colnames(data)==
input[[paste0('GroupVar',i)]])]})
}
joke=reactive({data[,which(colnames(data)==input[[paste0('GroupVar',1)]])]})
lapply(1:5, function(i) { output[[paste0('GroupOpt',i)]] = renderUI({
selectInput(paste0("GroupOpt",i), "Select group",multiple=TRUE,
sort(as.character(unique(Group[[paste0('Gcol',i)]])))
)
})})
output$try4 = renderText({print(paste0('it
is',input[[paste0('GroupVar',1)]]))})
output$try2 = renderText({print(dim( Group[[paste0('Gcol',1)]]()))})
output$try21 = renderText({print(class( Group[[paste0('Gcol',1)]]()))})
output$try3 =
renderText({print(which(colnames(data)==input[[paste0('GroupVar',1)]]))})
output$try = renderText({print(unique(as.character(joke())))})
}
# Run the application
shinyApp(ui = ui, server = server)

Answer 1

data[, which(colnames(data)=="Species")] is not a dataframe, this is the column Species, a factor. If you want to allow a one-column dataframe, do data[, which(colnames(data)=="Species"), drop=FALSE]
Replace your loop with the following one, and your app works (but maybe not as you expect; I'm not sure to understand what you want).
for (i in 1:5){
local({
ii <- i
Group[[paste0('Gcol',ii)]]=reactive({
data[,which(colnames(data)==input[[paste0('GroupVar',ii)]])]})
})
}