How to Filter data with R shiny

Question

I have a database consisting of

• Code of middle schools (code)
• Gender of the students ; 1:Male,2:Female (Cod_Sexe)
• Decision Concerning the student; A: Pass , R:Fail (Decision)
• Behaviour of the student during the year ; 0: Bad , 1:Good (Conduite).

This data is divided over 3 years: 2008,2011 and 2014. I am using R shiny, I created graphs for gender, decision and behaviour and just display the number of middle schools and students. Now I want to enable the user to filter this data according to a certain year. Here's the code:

USER INTERFACE

 ui <- fluidPage( 
    textOutput("inst_nbr"),
    textOutput("stunbr"),
    plotOutput("plot_decision"),
    plotOutput("genderdonut"),
    plotOutput("Conduite"),
    checkboxGroupInput(inputId = "YearSelect", "Select the corresponding year", 
      choices = levels(factor(Test2008$Year)), selected = levels(factor(Test2008$Year)))
)

inst_nbr : middle school number / stunbr: students number / plot_decision: histogram of the decisions(A/R) / genderdonut:donut chart for the gender distribution / Conduite:donut chart for the behavior / YearSelect: filter created from the database

Server

# CREATE YEAR FILTER
    TestFilter <- reactive({ # <-- Reactive function here
        Test2008 %>% 
            filter(Test2008$Year == input$YearSelect)
    })

# NBR OF INSTITUTIONS
    output$inst_nbr=  renderText({
        Test=TestFilter()
        length(unique(x = Test$Code))
        })

# PLOT DECISION DIAGRAM
    # % of each decison
    Per_A= 100*length(which(Test2008$Decision=='A'))/length(Test2008$Decision)
    Per_R= 100*length(which(Test2008$Decision=='R'))/length(Test2008$Decision)
    DecisionName=c('Accepté','Refusé')
    DecisionFraction=c(Per_A,Per_R)
    # Plot of decisions
    output$plot_decision=renderPlot({
        Test=TestFilter()
        barplot(height= DecisionFraction, names = DecisionName )
    })   

I applied the filter to the number of middle school, it works when I check each year alone, however when I check all the boxes it doesn't return the total. I don't know how to apply it to the graph on the other hand. In addition when I run the application I get these errors:

Warning: Error in : Problem with filter() input ..1 . x Input ..1 must be of size 111613 or 1, not size 0. i Input ..1 is Test2008$Year == input$YearSelect . 170: (Occurs when no box is checked)

And

Warning in Test2008$Year == input$YearSelect : longer object length is not a multiple of shorter object length

DUMMY DATA

Code     Cod_sexe    conduite   decision    year 
1002        1           1           A       2008
2065        1           0           R       2008
1002        2           1           A       2008
4225        2           1           R       2011        
2005        1           1           R       2011
1003        2           0           R       2014
2005        2           0           A       2014

Answer 1

If you want to make your plot reactive, you need to use your reactive dataset TestFilter rather than your static data.frame Test2008 to create the plot.

I'm nnot sure if this is the logic you want, but it should get you started.

Please check the following:

library(shiny)
library(dplyr)

Test2008 <- data.frame(
  stringsAsFactors = FALSE,
  Code = c(1002L, 2065L, 1002L, 4225L, 2005L, 1003L, 2005L),
  Cod_sexe = c(1L, 1L, 2L, 2L, 1L, 2L, 2L),
  conduite = c(1L, 0L, 1L, 1L, 1L, 0L, 0L),
  Decision = c("A", "R", "A", "R", "R", "R", "A"),
  Year = c(2008L, 2008L, 2018L, 2011L, 2011L, 2014L, 2014L)
)

ui <- fluidPage(
  checkboxGroupInput(
    inputId = "YearSelect",
    "Select the corresponding year",
    choices = unique(Test2008$Year),
    selected = unique(Test2008$Year)
  ),
  textOutput("inst_nbr"),
  textOutput("stunbr"),
  plotOutput("plot_decision"),
  plotOutput("genderdonut"),
  plotOutput("Conduite")
)

server <- function(input, output, session) {
  # CREATE YEAR FILTER
  TestFilter <- reactive({
    Test2008 %>% filter(Year %in% input$YearSelect)
  })
  
  # NBR OF INSTITUTIONS
  output$inst_nbr = renderText({
    length(unique(TestFilter()$Code))
  })
  
  # PLOT DECISION DIAGRAM
  output$plot_decision = renderPlot({
    req(TestFilter())
    # % of each decison
    Per_A = 100 * length(which(TestFilter()$Decision == 'A')) / length(TestFilter()$Decision)
    Per_R = 100 * length(which(TestFilter()$Decision == 'R')) / length(TestFilter()$Decision)
    DecisionName = c('Accepté', 'Refusé')
    DecisionFraction = c(Per_A, Per_R)
    barplot(height = DecisionFraction, names = DecisionName)
  })
}

shinyApp(ui, server)