Shiny + Ggplot: How to Subset Reactive Data Object

Shiny + ggplot: How to subset reactive data object?

(The complete server.R and ui.R really helped)

I'm not sure where you got the .() function from or the idea that geom_bar has a subset= parameter. But here's an updated renderPlot that doesn't seem to generate any errors at least

output$myplot = renderPlot({

  dd<-data.r()
  # ggplot with proper reference to reactive function <<data.r()>>
  s = ggplot(dd, aes(x=variable, fill=category))  +  

    # bars for categories A, B, Z: needs subsetting the data... but how?
     geom_bar(data=subset(dd, category %in% c("A","B")), aes(y=value), 
         stat="identity", position="stack") +
     geom_bar(data=subset(dd, category=="Z"), aes(y=-value), stat="identity") +

    # lines for categories R, S: same.
     geom_line(data=subset(dd, category=="R"), aes(y=value)) +
     geom_line(data=subset(dd, category=="S"), aes(y=value)) +

     scale_fill_manual(breaks = levels(dd$category), 
         values = mycolorgenerator(length(levels(dd$category))))

  print(s)
})

Mostly I changed the data= to explicit subset() calls

Subset a reactive dataframe in R

There are two ways of solving this:

1. Store dataframes inside reactiveValues objects (see: Creating a reactive dataframe with shiny apps for quite similar issue)
2. Coerce reactive expression to regular R variable via rt.df <- rt() before calling cor or other functions that don't handle reactives gracefuly.

R, shiny: reactive data.frame as a factor, set levels and order

When you use:

dataforplot <- reactive({
  plot_data <-  data() %>% 
    filter(Name %in% input$polymers) 
   plot_data$ID_Polymer <- factor(plot_data$ID_Polymer, 
          levels =plot_data$ID_Polymer[ order(plot_data[["Content"]])])
})

The last line of whatever is inside your reactive() is returned as the value of that reactive element. Hence, in your case plot_data$ID_Polymer(which is not a dataframe, but a factor column of the dataframe) is returned as dataforplot(). This is the reason for the error. Change you dataforplot() definition to:

dataforplot <- reactive({
  plot_data <-  data() %>% 
    filter(Name %in% input$polymers) 
   plot_data$ID_Polymer <- factor(plot_data$ID_Polymer, 
          levels =plot_data$ID_Polymer[ order(plot_data[["Content"]])])
   # Add return statement for returning the dataframe
   return(plot_data)
})

How to create a shiny reactive function with input in a separate R

You could pass input as argument to the reactive function:

newdate <- function(input) {
  reactive({
    req(input$range)
    df %>% filter(between(date, input$range[1], input$range[2]))
  })
}

The call to the function in the server is then:

plot <- newdate(input)() %>% ...

R Shiny ggplot reactive to varSelectInput

Welcome to stackoverlfow.

There are a few things you have to change in order to have a functional app. I put here a summary of the things I saw, and details within the code as comments.

1. Prepare your data, you should consider creating variables
2. Do not put a whole vector with duplicated values as choices argument in a selectInput, you should pass the distinct options.
3. It is a good idea to select a value whenever is possible. that way your app will launch with something to show as default.
4. Use the inputs to filter the data.
5. selectInput create a string value, there for, your should use aes_string in your ggplot mapping argument.

library(shiny)
library(tidyverse)

# You have to Adequate your data: You have to create a dete variable
# in order to make the `dateRangeInput` work. You can do that using
# `year`, `month` and `day` variables as follow.
flights <- nycflights13::flights %>% 
    mutate(
        date = as.Date(paste(year, month, day, sep = "-"))
    )

ui <- navbarPage(
    title = "NYC Flights",
    tabPanel(
        title = "Flights",
        sidebarPanel(
            h4("Flight Inputs"),
            # The choices argument should be the unique
            # list of arilines, not the whole vector with
            # duplicates
            selectInput(
                "airline",
                label = "Select Airline",
                choices = unique(flights$carrier), 
                selected = 'UA' # It is a good idea to select a value
                # visible when you launch the app
            ),
            dateRangeInput(
                "dates",
                label = "Dates",
                start = min(flights$date),
                end = max(flights$date)
                ),
            varSelectInput(
                "X_Axis",
                label = "Select Variable 1",
                data = flights,
                selected = "date" # selecting one
            ),
            varSelectInput(
                "Y_Axis",
                label = "Select Variable 2",
                data = flights,
                selected = "dep_delay" # selecting one
            )
        ),

        mainPanel(
            plotOutput("plot")
        )

    )

)

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

    output$plot <- renderPlot({
        flights %>% 
            # Use your inputs to filter the data
            filter(date >= input$dates[1], date <= input$dates[2], carrier == input$airline) %>% 
            # since the selectImput create a character element, you should use 
            # ase_string() to map the x an y variables
            ggplot(aes_string(x = input$X_Axis, y = input$Y_Axis)) +
            geom_point()
    })

}

shinyApp(ui, server)

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