Begginer in Shiny - Problems with ggplot geom_tile

Question

I am triying to make a heatmap with ggplot and Shiny in R, but the plot is not shown as I expected. I'm using data which have a diffrent structure than Shiny-RStudio exemples and maybe that's why I didn't have a good result.

My data table contains 152013 lines and 7 variabls (zone, season, week, fishingfleet, length, category, vul1.indicator). I want to make a heatmap of the variable "vul1.indicator" with x=week and y=zone and the shiny app user can choose the category and season. My problem is when I change the choices for "season" and "category" in the sidebar only the legend change but not the plot. It seems like there is no link between the plot section and choices. I don't know where I made up mistake. Can you help me please?

This is an example of my table (I have 10 choices for "category" and 3 choices for "season":

> Vul1MoyZoneAgr
    zone    season week fishingfleet length category vul1.indicator
1     Z1 2012-2013    1          CAD     T1   CAD-T1              1
2     Z1 2012-2013    2          CAD     T1   CAD-T1              1
3     Z1 2012-2013    3          CAD     T1   CAD-T1              1
4     Z1 2012-2013    4          CAD     T1   CAD-T1              1
5     Z1 2012-2013    5          CAD     T1   CAD-T1              1
6     Z1 2012-2013    6          CAD     T1   CAD-T1              1
7     Z1 2012-2013    7          CAD     T1   CAD-T1              1
8     Z1 2012-2013   46          CAD     T1   CAD-T1              1
9     Z1 2012-2013   47          CAD     T1   CAD-T1              1
10    Z1 2012-2013   48          CAD     T1   CAD-T1              1
11    Z1 2012-2013   49          CAD     T1   CAD-T1              1
12    Z1 2012-2013   50          CAD     T1   CAD-T1              1
13    Z1 2012-2013   51          CAD     T1   CAD-T1              1
14    Z1 2012-2013   52          CAD     T1   CAD-T1              1

And this is my code:

library(ggplot2)
Vul1MoyZoneAgr <- read.table("C:/Users/user/Documents/Vul1MoyZoneAgr.txt", sep="\t",quote="", dec=",", header = TRUE)
Vul1MoyZoneAgr$zone <- factor(Vul1MoyZoneAgr$zone, levels = c("Z1", "Z2", "Z3", "Z4", "Z5", "Z6", "Z7", "Z8", "Z9", "Z10", "Z11", "Z12", "Z13", "Z14", "Z15", "ZI", "ZJ"))
Vul1MoyZoneAgr$week <- factor(Vul1MoyZoneAgr$week, levels = c("40","41", "42", "43", "44", "45", "46", "47", "48", "49", "50", "51", "52", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20"))
# Define UI ----
ui <- fluidPage(
    
    
    titlePanel("Vulnerability indicator"),
    
    
    sidebarLayout(
        
        sidebarPanel(
            
            selectInput("category", "category:", 
                        choices = c(unique(Vul1MoyZoneAgr$category))),
            selectInput("season", "season:",
                        choices = c(unique(Vul1MoyZoneAgr$season))),
            
            
        ),
        
        mainPanel(
            
            # Output: Formatted text for caption ----
            h3(textOutput("caption")),
            
            # Output ----
            
                plotOutput("vul1.indicatorPlot")

            
        )
    )
)

# Define server logic ----
server <- function(input, output) {

    # Compute the formula text ----
    # This is in a reactive expression since it is shared by the
    # output$caption and output$vul1.indicatorPlot functions
    formulaText <- reactive({
        paste("vulnerability indicator ~", input$category, "~", input$season)
})
    # Return the formula text for printing as a caption ----
    output$caption <- renderText({
        formulaText()
    })
    
    # Reactive expression for the data subsetted to what the user selected
    
    
   
    # Generate a plot of the requested season and category ----

    output$vul1.indicatorPlot <- renderPlot({
        ggplot(as.formula(formulaText()),
            data = Vul1MoyZoneAgr, mapping = aes(x=week, y=zone, fill=vul1.indicator)) + theme_bw() +
            geom_tile(aes(fill = vul1.indicator), colour = "white") + scale_fill_gradient(low = "#F2E8EC", high = "#990000", limits=c(0, 7), breaks=seq(0,7,by=1)) +
            labs(fill = "Vul. Ind.") +
            theme(strip.background = element_rect(colour="black", fill="white"), axis.text.x = element_text(face= "bold", size = 10), axis.text.y = element_text(face= "bold",size = 10), axis.title.x = element_text(face= "bold",size = 12), axis.title.y = element_text(face= "bold",size = 12), strip.text.y = element_text(face= "bold",size = 10),strip.text.x = element_text(face= "bold",size = 12), legend.text = element_text(face= "bold",size = 12), legend.title = element_text(face= "bold",size = 12), legend.key.size = unit(1.5, "cm"), legend.key.width = unit(0.5,"cm"), panel.grid.major=element_line(colour = "white"))
        })
    
}


shinyApp(ui, server)

Thank you!

score 0 · Accepted Answer · answered Mar 05 '21 at 19:21

The short answer is you're not using any sort of reactive value in generating the plot, i.e. when you change your selections, it's not changing how the plot is calculated. I mean you even already have a commented section of your code that's blank for where this would go.

You need something along the lines of a dataset that gets updated when one of the selector changes:

displayData <- reactive( <code to subset data> )

Then use this when creating your plot

ggplot(data = displayData()...

score 0 · Answer 2 · answered Mar 08 '21 at 15:30

Thank you Marcus! It works now.

I used this code:

# Reactive expression for the data subsetted to what the user selected
    filteredData <- reactive({
        req(input$category, input$season)
        filter(Vul1MoyZoneAgr, category == input$category, season == input$season)
    
    })

Then:

ggplot(data = filteredData(), ...

Begginer in Shiny - Problems with ggplot geom_tile

2 Answers2