bars missing when using shiny to create ggplot bar chart - r

Question

I used shiny and created a app.R file to hope to build a bar chart with ggplot. I also used checkboxGroupInput to create a 2 check boxes to control the condition. While the total number of bars should be 28 after all boxes are checked, but the maximum seemed to allow only 17 bars for some reason. So some bars (row of data) are missing. The missing bars don't seems to have a pattern. Can someone please help ?
dataset:https://drive.google.com/open?id=1fUQk_vMJWPwWnIMbXvyd5ro_HBk-DBfc
my code:
midterm <- read.csv('midterm-results.csv')
library(dplyr)
library(tidyr)
# get column number for response time
k <- c(33:88)
v <- c()
for (i in k){
if (i%%2 == 1){
v <- c(v,i)
}
}
#average response time by question
time <- midterm[ , v]
new.col.name <- gsub('_.*', "", colnames(time))
colnames(time) <- new.col.name
avg.time <- data.frame(apply(time, 2, mean))
avg.time$question <- rownames(avg.time)
colnames(avg.time) <- c('response_time', 'question')
rownames(avg.time) <- NULL
avg.time$question <- factor(avg.time$question,
levels = c('Q1','Q2','Q3','Q4','Q5','Q6','Q7','Q8.9',
'Q10','Q11','Q12.13','Q14','Q15','Q16','Q17',
'Q18','Q19','Q20','Q21','Q22','Q23','Q24','Q25',
'Q26','Q27','Q28','Q29','Q30'))
avg.time$question_type <- c(1,0,1,0,1,0,1,1,1,1,1,0,1,1,1,1,0,1,1,1,0,0,0,0,1,1,0,0)
# I did this manually because the there when data was imported into the midterm.csv,
# q8 & 9, q12 &13 were accidentally merged (28 v.s 30 question)
avg.time$question_type <- ifelse(avg.time$question_type == 1,
'googleable', 'not googleable')
avg.time$question_type <- factor(avg.time$question_type,
levels = c('googleable', 'not googleable'))
library(shiny)
library(ggplot2)
ui <- fluidPage(
checkboxGroupInput(inputId = "type",
label = "select question type",
choices = levels(avg.time$question_type),
selected = TRUE),
plotOutput('bar')
)
server <- function(input, output) {
output$bar <- renderPlot({
ggplot(avg.time[avg.time$question_type==input$type, ],
aes(x=question, response_time)) +
geom_bar(aes(fill = question_type), stat='identity', width = 0.5)
}, height =500, width = 1000)
}
shinyApp(ui = ui, server = server)

Answer 1

library(shiny)
library(ggplot2)
ui <- fluidPage(
checkboxGroupInput(inputId = "type", label = "select question type",
choices = levels(avg.time$question_type), selected = TRUE),
plotOutput('bar')
)
server <- function(input, output) {
data <- reactive(avg.time[avg.time$question_type %in% input$type, ])
output$bar <- renderPlot({
ggplot(data(),
aes(x=question, response_time)) + geom_bar(stat='identity', width = 0.5,
aes(fill = question_type))
}, height =500, width = 1000)
}
shinyApp(ui = ui, server = server)
of course you can use avg.time[avg.time$question_type %in% input$type, ] inside ggplot2 but reactivity is better.