r shiny code - selectInput with factor variables - r

Question

I am building a shiny app. In the drop down menu I have the categories of a factor variable. I think the problem is in the server but I dont know how to fix it.
Also, I would like that to add a vertical in the histograms at 15 when the colour chosen is yellow, and a vertical line at 20 when the colour chose in the histogram is Red. Can you please help me with my code?
Thanks
library(shiny)
# Creating a fake data frame
categories <- c("A", "B", "c")
values <- c(12, 15, 20)
data <- merge(categories, values)
# Define UI for application
ui <- shinyUI(fluidPage(
# Title panel
titlePanel(title = h1("Title", align = "center")),
sidebarLayout(
# Sidebar panel
sidebarPanel(
# Options
selectInput(inputId = "xcol", label = "Select", choices = levels(data$x)),
br(),
#Colours histogram
radioButtons(inputId = "colour", label = strong("Select the colour of
histogram"), choices = c("Yellow", "Red"), selected = "Yellow"),
br(),
#Bins for histogram
sliderInput(inputId = "bins", label = "Select the number of Bins for the
histogram", min=5, max = 25, value = 15),
br(),
#Density curve
checkboxInput(inputId = "density", label = strong("Show Density Curve"),
value = FALSE),
# Display this only if the density is shown
conditionalPanel(condition = "input.density ==true",
sliderInput(inputId = "bw_adjust",
label = "Bandwidth adjustment:",
min = 0.2, max = 3, value = 1, step = 0.2))
),
# Main Panel
mainPanel(
#plot histogram
plotOutput("plot"),
# Output: Verbatim text for data summary
verbatimTextOutput("summary"))
)))
# Define server logic
server <- shinyServer(function(input, output) {
output$plot <-renderPlot({
hist(data[input$xcol, data$x], breaks = seq(0, max(data[input$xcol,
data$x]), l= input$bins+1), col = "lightblue",
probability = TRUE, xlab = "Values", main = "")
abline(v = mean(data[input$xcol, data$x]), col = "red", lty = 2)
title(main = levels(data$x[input$xcol]))
if (input$density) {
dens <- density(data[input$xcol, data$x], adjust = input$bw_adjust)
lines(dens, col = "blue", lwd = 1)
}
# Generate the summary
output$summary <- renderPrint({
xcol <- xcolInput()
summary(xcol)
})
})
})
# Run the application
shinyApp(ui = ui, server = server)

Answer 1

It looks like you were subsetting data incorrectly. I created a reactive expression for the data subset: data2(), and used that to make the plot outputs. I also added the vertical lines you mention with an if(){...}else{...} statement.
library(shiny)
# Creating a fake data frame
categories <- c("A", "B", "c")
values <- c(12, 15, 20)
data <- merge(categories, values)
# Define UI for application
ui <- shinyUI(fluidPage(
# Title panel
titlePanel(title = h1("Title", align = "center")),
sidebarLayout(
# Sidebar panel
sidebarPanel(
# Options
selectInput(inputId = "xcol", label = "Select", choices = levels(data$x)),
br(),
#Colours histogram
radioButtons(inputId = "colour", label = strong("Select the colour of
histogram"), choices = c("Yellow", "Red"), selected = "Yellow"),
br(),
#Bins for histogram
sliderInput(inputId = "bins", label = "Select the number of Bins for the
histogram", min=5, max = 25, value = 15),
br(),
#Density curve
checkboxInput(inputId = "density", label = strong("Show Density Curve"),
value = FALSE),
# Display this only if the density is shown
conditionalPanel(condition = "input.density ==true",
sliderInput(inputId = "bw_adjust",
label = "Bandwidth adjustment:",
min = 0.2, max = 3, value = 1, step = 0.2))
),
# Main Panel
mainPanel(
#plot histogram
plotOutput("plot"),
# Output: Verbatim text for data summary
verbatimTextOutput("summary"))
)))
# Define server logic
server <- shinyServer(function(input, output) {
data2 <- reactive({data[as.character(data$x)==input$xcol, "y"]})
output$plot <-renderPlot({
hist(data2(), breaks = seq(0, max(c(1, data2()), na.rm=TRUE), l= input$bins+1), col = input$colour,
probability = TRUE, xlab = "Values", main = "")
abline(v = mean(data2()), col = "red", lty = 2)
title(main = input$xcol)
if (input$density) {
dens <- density(data2(), adjust = input$bw_adjust)
lines(dens, col = "blue", lwd = 1)
}
if(input$colour=="Red"){
abline(v=20)}else{abline(v=15)}
# Generate the summary
output$summary <- renderPrint({
#xcol <- xcolInput()
summary(data2())
})
})
})
# Run the application
shinyApp(ui = ui, server = server)