Include multiple different graphics in shiny app - r

Question

I am attempting to build my first shiny app. I need to include multiple graphics (about 50) and I am having problems selecting them based on their label from the dropdown control. I am able to show the first one but I don't know how to display the other ones on the main panel. I currently have 3 on the dropdown control but only the first one works. How do I make lambda2, lambda3 and so on show on the main panel? I also would like to dynamically plot the number of years selected on the slider. Here is the code:
library(shiny)
library(tidyverse)
library(shinythemes)
library(plotly)
library(scales)
library(shinyWidgets)
library(shinydashboard)
# Define input choices
type <- c("lambda","lambda2","lambda3")
table <- structure(list(year = 1991:2010,
lambda = c(0.68854, 0.75545,
1.63359, 1.22282, 1.70744, 1.09692, 0.51159, 1.3904, 1.09132,
0.59846, 0.43055, 0.80135, 0.69027, 0.65646, 0.95485, 1.04818,
0.67859, 1.00461, 1.16665, 1.28203)), row.names = c(NA, -20L), class = "data.frame")
# Define UI
ui <- fluidPage(
navbarPage("Fish",
windowTitle = "Fish Graphs",
sidebarPanel(
h3("Select Graphics to Visualize"),
selectInput(inputId = "graphtype",
label = "Graphic",
choices = type,
selected = "lambda"),
sliderInput(inputId = "Yearslider",
label="Years to plot",
sep="",
min=1991,
max=2011,
value=c(1991,2011))),
mainPanel(plotOutput("plot"))))
####################################
server<- function (input, output, session) {
session$onSessionEnded(function() {
stopApp()
})
output$plot <- renderPlot({
xlabels <- 1991:2011
ggplot(table,aes(year,lamda)) + geom_line(size=1.5,colour="blue") + geom_point(colour="orange",size=4) +
scale_x_continuous("",breaks = xlabels) +
theme(axis.text.x = element_text(angle = 45, vjust = 0.5)) +
labs(x="",y=expression("Lambda ("~lambda *")"),title="Population growth rate - fraction per year- \nof Delta Smelt")
if (input$lambda2 == TRUE) {
xlabels <- 1991:2011
ggplot(table,aes(year,lamda)) + geom_line(size=1.5,colour="green") + geom_point(colour="orange",size=4) +
scale_x_continuous("",breaks = xlabels) +
theme(axis.text.x = element_text(angle = 45, vjust = 0.5)) +
labs(x="",y=expression("Lambda ("~lambda *")"),title="Population growth rate - fraction per year- \nof Delta Smelt")
}
if (input$lambda3 == TRUE) {
xlabels <- 1991:2011
ggplot(table,aes(year,lamda)) + geom_line(size=1.5,colour="red") + geom_point(colour="orange",size=4) +
scale_x_continuous("",breaks = xlabels) +
theme(axis.text.x = element_text(angle = 45, vjust = 0.5)) +
labs(x="",y=expression("Lambda ("~lambda *")"),title="Population growth rate - fraction per year- \nof Delta Smelt")
}
})
}
shinyApp(ui = ui, server = server)

Answer 1

The main issue with your code is that the element of the input list containing the lambda choice is called graphtype. Using input$lambda2 returns NULL. Do e.g. input$graphtype == "lambda2" instead. Also, if you want to switch between different choices you have to use an if-else with a branch for "each" choice or perhaps use switch as I do below. To make your plot react to the year slider I use an reactive which filters the data for years in the selected range. Also, instead of duplicating the ggplot code I would suggest to move it in a separate function outside of the server which also makes it easier to debug the code.
plot_fun <- function(.data, point.color = "black") {
breaks <- unique(.data$year)
ggplot(.data, aes(year, lambda)) +
geom_line(size = 1.5, colour = "blue") +
geom_point(colour = point.color, size = 4) +
scale_x_continuous("", breaks = breaks) +
theme(axis.text.x = element_text(angle = 45, vjust = 0.5)) +
labs(x = "", y = expression("Lambda (" ~ lambda * ")"), title = "Population growth rate - fraction per year- \nof Delta Smelt")
}
server <- function(input, output, session) {
session$onSessionEnded(function() {
stopApp()
})
plot_data <- reactive({
table[table$year >= input$Yearslider[1] & table$year <= input$Yearslider[2], ]
})
output$plot <- renderPlot({
switch(input$graphtype,
"lambda" = plot_fun(plot_data(), point.color = "orange"),
"lambda2" = plot_fun(plot_data(), point.color = "purple"),
"lambda3" = plot_fun(plot_data(), point.color = "green")
)
})
}
shinyApp(ui = ui, server = server)