Using shiny input values in a ggplot aes

Question

I'm trying to implement these 3 lines of code, which is my desired output, in Shiny.

install.packages("ggalt")
library(ggalt)

health <- read.csv("https://raw.githubusercontent.com/selva86/datasets/master/health.csv")
health$Area <- factor(health$Area, levels=as.character(health$Area)) # did something for graph 

ggplot(health, aes(x=pct_2013, xend=pct_2014, y=Area))+
    geom_dumbbell()

In Shiny, I want a user to be able to choose starting and ending points of a lollipop graph. I also want a user to be able to choose a categorical variable (among many categorical variables -- even though for now, the example data only has one categorical variable) that would show up on the y-axis. Below is what I worked on so far, literally replacing all variables to input variables (so I think it should work but it doesn't..)

ui<-pageWithSidebar(
  headerPanel('Lollipop Chart'),
  sidebarPanel(
    selectInput('xcol', 'X Variable', names(health), selected=names(health)[1]),
    selectInput('val1', 'Starting Value', names(health), selected=names(health)[3]), 
    selectInput('val2', 'Ending Value', names(health), selected=names(health)[2])   ),
  mainPanel(
    plotOutput('plot1')
  )
)

server<-function(input, output, session) {

   health < read.csv("https://raw.githubusercontent.com/selva86/datasets/master/health.csv")
health$Area <- factor(health$Area, levels=as.character(health$Area)) # did something for graph 

  selectedData <- reactive({
    health[, c(input$xcol, input$val1, input$val2)]
  }) 

  output$plot1 <- renderPlot({
ggplot(selectedData(), aes(x=input$val1, xend=input$val2, y=input$xcol))+
    geom_dumbbell()
  })
}

shinyApp(ui, server)

Could anyone help why am I not getting the desired output? :(

Wilmar van Ommeren Wilmar van Ommeren · Accepted Answer · 2019-10-28T11:15:24

The desired plot doesn't show up because you are calling ggplot in a different way. In your shiny app the selected column names are strings:

ggplot(health, aes(x='pct_2013', xend='pct_2014', y='Area'))+
    geom_dumbbell()

Replace the aes with aes_string and it will work.

ggplot(health, aes_string(x='pct_2013', xend='pct_2014', y='Area'))+
       geom_dumbbell()

Using shiny input values in a ggplot aes

1 Answers