Change map colourfill based on user selection - r

Question

It's been a while since i'm having this problem. My current shiny app is not able to communicate with the user selection. It is supposed to show a colour fill variation across different region when a user makes a selection. However, it seems like the map is not showing it. My best guess is that it is not reading the 'pal' function correctly, and not able to capture the selection that the user input.
any kind of help would be great.
library(datasets)
library(dplyr)
library(ggplot2)
library(gridExtra)
library(leaflet)
library(leaflet.extras)
library(Matrix)
library(readxl)
library(rgdal)
library(shiny)
library(stringr)
library(tidyverse)
library(tidyr)
library(RColorBrewer)
cf <- read.csv("datafile.csv")
sgmap55 <-readOGR("shapefile.kml")
bins <-c(1,50,100,150,200)
pal <- colorBin("Blues", domain = NULL, bins = bins, na.color = "#808080")
#5) setting for the labels.
labels <- sprintf(
"<strong>%s</strong><br/>%g respondents </sup>",
cf$planarea, cf$planarea)%>% lapply(htmltools::HTML)
##Section C: ShinyApp starts here
ui <- fluidPage(
titlePanel("Brand Interaction with Regions"),
sidebarLayout(
sidebarPanel(
radioButtons("brand", "Select First Brand:", choices = colnames(cf[,c(3,4,5,6,7,8,9,10,11,12,13,14)]))),
mainPanel(
leafletOutput("sgmap2")
)
)
)
server <- function(input, output, session) {
output$sgmap2 <- renderLeaflet({
selected_brand <- input$brand
leaflet() %>%
addTiles() %>%
addResetMapButton()%>%
clearMarkers()%>%
addProviderTiles("OpenStreetMap") %>%
setView(103.8198,1.3521,11)%>%
addPolygons(data = sgmap55,
highlight = highlightOptions(
weight = 5,
color = "#666666",
fillOpacity = 0.7,
fillColor = pal(input$selected_brand),
bringToFront = TRUE))
})
}
shinyApp(ui = ui, server = server)

Answer 1

manage to solve it with below code in between the server portion:
req(input$brand)
cpop <- cf[[input$brand]]