stacked geom_bar in shiny that depends on select input - r

Question

I'm trying to include a stacked bar chart in shiny that depends on a select input. It works fine outside of shiny but in shiny it is not displaying multiple bars.
Code:
library(shiny)
library(ggplot2)
# Define UI ----
ui <- fluidPage(
# Application title
titlePanel("Group fairness analysis"),
# Sidebar
sidebarLayout(
sidebarPanel(
selectInput("group", "Group:",
c("Age" = "age",
"Gender" = "gender",
"Region" = "region",
"Ethnicity"="ethnicity"))
),
# Show a plot of the generated distribution
mainPanel(
h3("Accuracy bar chart"),
plotOutput("accPlot")
)
)
)
# Define server logic ----
server <- function(input, output) {
output$accPlot <- renderPlot({
g2 <- ggplot(df %>% count(get(input$group),correct) , aes(x=c(input$group),y=n,fill=as.factor(correct))) +
geom_bar(stat="identity",position=position_fill())+
scale_y_continuous(labels = scales::percent) +
geom_text(aes(label = paste0((n/nrow(df))*100,"%")), position = position_fill(vjust = 0.5), size = 5)+
theme_bw()+
ylab("")+
coord_flip()
g2
})
}
shinyApp(ui, server)
Sample data
# data -----------------------------------------------------------
n<-20 #number of users
threshold <- 60 #threshold in risk score for referral to YS
df <- data.frame(age = rep(0,n),
gender = rep(0,n),
ethnicity = rep(0,n),
region = rep(0,n),
score = rep(0,n),
referred = rep(0,n),
target = rep(0,n))
df$age <- as.factor(sample(c(15,16,17),size=n,replace=TRUE))
df$gender <- as.factor(sample(c('M','F'),size=n,replace=TRUE))
df$ethnicity<- as.factor(sample(c('European','Maori','Pacific','other'),size=n,replace=TRUE))
df$region<-as.factor(sample(c('North','Mid','South'),size=n,replace=TRUE))
df$score<-runif(n,min=0,max=100)
df$target<-sample(c(0,1),size=n,replace = TRUE)
df[which(df$score>=threshold),"referred"]<-1
df$colour<-rep(0,n)
df[which(df$referred==1 & df$target==1),"colour"]<-1
df[which(df$referred==1 & df$target==0),"colour"]<-2
df[which(df$referred==0 & df$target==1),"colour"]<-3
df[which(df$referred==0 & df$target==0),"colour"]<-4
df$correct<-rep(0,n)
df[which(df$referred==0 & df$target==0),"correct"]<-1
df[which(df$referred==1 & df$target==1),"correct"]<-1
df[which(df$referred==0 & df$target==1),"correct"]<-0
df[which(df$referred==1 & df$target==0),"correct"]<-0
It should look like

Answer 1

Your input$group from selectInput is a string, not a variable symbol. You can convert it to a symbol for your ggplot with rlang::sym and evaluate with !!.
In addition, your aesthetic for ggplot can use aes_string and refer to your column names as strings.
And would convert your correct column to a factor separately.
df$correct <- as.factor(df$correct)
...
g2 <- ggplot(df %>% count(!!rlang::sym(input$group), correct), aes_string(x=c(input$group), y="n", fill="correct")) +
...