I have a nice plotting function done with ggplot that has also built in functionality for plotting vertical lines and these are part of my larger Shiny app. I tried to make a minimal reproducible example for my problem. Here it is:
library(shiny)
library(ggplot2)
ui <- fluidPage(
fluidRow(
column(6, offset=1,
plotOutput("plot", width="100%", height="500px")
)
),
fluidRow(
column(2, offset=1,
actionButton(inputId="go", label="Plot")
),
column(2, offset=1,
selectInput(inputId="number", label="Number of lines:",
choices=list("No lines"="0",
"One line"="1",
"Two lines"="2",
"Three lines"="3"))
)
),
fluidRow(
uiOutput("dynamic")
)
)
server <- function(input, output, session) {
# Function for n number of input boxes for
# vertical line interception points in UI
vertical_line_UI <- function(n) {
fluidRow(
column(4, offset=1,
numericInput(inputId=sprintf("line%s", n),
label=sprintf("Line%s:", n),
value=5))
)
}
# Rendering above in UI
output$dynamic = renderUI({
if (as.integer(input$number) > 0) {
lapply(1:as.integer(input$number), vertical_line_UI)
}
})
# Vertical line interception points
lines <- eventReactive(input$go, {
if (as.integer(input$number) > 0 ) {
c(input$line1, input$line2, input$line3)
} else {
NULL
}
})
# Plot function
plot_function <- function(data, lines=NULL) {
p <- ggplot(data=data.frame(x=1:10, y=1:10),
aes(x=x, y=y)) + geom_line() + theme_bw()
if (!is.null(lines)) {
for (n in 1:length(lines)) {
p <- p + geom_vline(xintercept=lines[n])
}
}
return(p)
}
# Rendering plot
plot <- eventReactive(input$go, {
plot_function(lines=lines())
})
output$plot <- renderPlot({
plot()
})
}
shinyApp(ui = ui, server = server)
What I would like to do is have a nicer way than manually writing c(input$line1, input$line2, input$line3, ..., input$lineN) for N number of vertical lines. I would probably cap it at 10-15 anyways.
So I suppose my problem could be narrowed down how to express
lines <- eventReactive(input$go, {
if (as.integer(input$number) > 0 ) {
c(input$line1, input$line2, input$line3)
} else {
NULL
}
})
in more fluid way for N number of inputs instead of manually writing each one of them down. If I five vertical lines I would only have 5 input variables etc.
