Boxplots in R Shiny App showing only flat lines - r

Question

I have looked at similar posts and the responses don't seem to answer my question. I am trying to develop an R Shiny App (This is my first Shiny App) to draw a boxplot for some data. I am adapting it from some code that produces accurate boxplots in the console. The plots should look similar to this (I did simplify the labels for the app):
correct plot
When I run the app, I see the following:
app plot
Here is some reproducible code. Any insights would be greatly appreciated:
library(dplyr)
library(ggplot2)
library(shiny)
AlkCalcs2 <- data.frame(matrix(ncol = 6, nrow = 250))
AlkCalcs2$climate <- sample.int(2, 250, replace = TRUE)
AlkCalcs2$block <- sample.int(3, 250, replace = TRUE)
AlkCalcs2$treatment <- factor(sample.int(4, 250, replace = TRUE),
labels = c("Control", "Compost", "Basalt", "Basalt and Compost"))
AlkCalcs2$pre_dilution_alk_endp <- rnorm(250, 91, 58)
AlkCalcs2$pre_dilution_alk_infl <- rnorm(250, 65, 59)
AlkCalcs2$pre_dilution_alk_gran <- rnorm(250, 72, 55)
# Define server logic
server <- function(input, output, session) {
output$boxplot <- renderPlot({
ggplot(data = filter(AlkCalcs2,
climate == input$climate,
block %in% input$block)) +
geom_boxplot(mapping = aes(x = treatment, y = input$method)) +
labs(y = "Alkalinity",
x = element_blank(),
title = paste("Climate ", input$climate, sep = ""),
subtitle = paste("Block(s) ", input$block, sep = "")) +
theme(plot.title = element_text(size = 16, hjust = 0.5),
plot.subtitle = element_text(size = 16, hjust = 0.5),
axis.text = element_text(size = 12),
axis.title = element_text(size = 14))
})
}
# Define UI for application that draws a boxplot
ui <- fluidPage(
# Application title
titlePanel("Soybean Titration Analysis"),
# Sidebar with inputs
sidebarLayout(
sidebarPanel(
radioButtons(inputId = "method",
label = "Alkalinity Calculation Method:",
choiceNames = c('Endpoint', 'Inflection Point', 'Gran Plotting'),
choiceValues = c('pre_dilution_alk_endp',
'pre_dilution_alk_infl',
'pre_dilution_alk_gran')),
radioButtons(inputId = "climate",
label = "Select Climate:",
choices = c(1, 2)),
checkboxGroupInput(inputId = "block",
label = "Select Block (Choose at least one):",
choices = c(1, 2, 3),
selected = 1)
),
# Show a boxplot of the data
mainPanel("Boxplot", plotOutput('boxplot'))
)
)
# Run the application
shinyApp(ui = ui, server = server)

Answer 1

It's more a ggplot issue than Shiny issue. Your plot data isn't right.
library(dplyr)
library(ggplot2)
library(shiny)
AlkCalcs2 <- data.frame(matrix(ncol = 6, nrow = 250))
AlkCalcs2$climate <- sample.int(2, 250, replace = TRUE)
AlkCalcs2$block <- sample.int(3, 250, replace = TRUE)
AlkCalcs2$treatment <- factor(sample.int(4, 250, replace = TRUE),
labels = c("Control", "Compost", "Basalt", "Basalt and Compost"))
AlkCalcs2$pre_dilution_alk_endp <- rnorm(250, 91, 58)
AlkCalcs2$pre_dilution_alk_infl <- rnorm(250, 65, 59)
AlkCalcs2$pre_dilution_alk_gran <- rnorm(250, 72, 55)
AlkCalcs2[['pre_dilution_alk_endp']]
# Define server logic
server <- function(input, output, session) {
output$boxplot <- renderPlot({
plot_data <- filter(AlkCalcs2,
climate == input$climate,
block %in% input$block)
ggplot(data = plot_data) +
geom_boxplot(mapping = aes(x = treatment, y = .data[[input$method]])) +
labs(y = "Alkalinity",
x = element_blank(),
title = paste("Climate ", input$climate, sep = ""),
subtitle = paste("Block(s) ", input$block, sep = "")) +
theme(plot.title = element_text(size = 16, hjust = 0.5),
plot.subtitle = element_text(size = 16, hjust = 0.5),
axis.text = element_text(size = 12),
axis.title = element_text(size = 14))
})
}
# Define UI for application that draws a boxplot
ui <- fluidPage(
# Application title
titlePanel("Soybean Titration Analysis"),
# Sidebar with inputs
sidebarLayout(
sidebarPanel(
radioButtons(inputId = "method",
label = "Alkalinity Calculation Method:",
choiceNames = c('Endpoint', 'Inflection Point', 'Gran Plotting'),
choiceValues = c('pre_dilution_alk_endp',
'pre_dilution_alk_infl',
'pre_dilution_alk_gran')),
radioButtons(inputId = "climate",
label = "Select Climate:",
choices = c(1, 2)),
checkboxGroupInput(inputId = "block",
label = "Select Block (Choose at least one):",
choices = c(1, 2, 3),
selected = 1)
),
# Show a boxplot of the data
mainPanel("Boxplot", plotOutput('boxplot'))
)
)
# Run the application
shinyApp(ui = ui, server = server)