Validates no intersection between two vectors

validate_no_intersection(x, y, msg)

data <- data.frame(
  id = c(1:10, 11:20, 1:10),
  strata = rep(c("A", "B", "C"), each = 10)
)

ui <- fluidPage(
  selectInput("ref1", "Select strata1 to compare",
    choices = c("A", "B", "C"),
    selected = "A"
  ),
  selectInput("ref2", "Select strata2 to compare",
    choices = c("A", "B", "C"),
    selected = "B"
  ),
  verbatimTextOutput("summary")
)

server <- function(input, output) {
  output$summary <- renderText({
    sample_1 <- data$id[data$strata == input$ref1]
    sample_2 <- data$id[data$strata == input$ref2]

    validate_no_intersection(
      sample_1, sample_2,
      "subjects within strata1 and strata2 cannot overlap"
    )
    paste0(
      "Number of subject in: reference treatment=", length(sample_1),
      " comparions treatment=", length(sample_2)
    )
  })
}
if (interactive()) {
  shinyApp(ui, server)
}