Shiny slider examples with the intrval R package

March 8, 2018
By

(This article was first published on Peter Solymos - R related posts, and kindly contributed to R-bloggers)

The intrval R package is lightweight (~11K), standalone (apart from importing from graphics, has exactly 0 non-base dependency), and it has a very narrow scope: it implements relational operators for intervals — very well aligned with the tiny manifesto. In this post we will explore the use of the package in two shiny apps with sliders.

The first example uses a regular slider that returns a single value. To make that an interval, we will use standard deviation (SD, sigma) in a quality control chart (QCC). The code is based on the pistonrings data set from the qcc package. The Shewhart chart sets 3-_sigma_ limit to indicate state of control. The slider is used to adjusts the sigma limit and the GIF below plays is as an animation.

library(shiny)
library(intrval)
library(qcc)

data(pistonrings)
mu <- mean(pistonrings$diameter[pistonrings$trial])
SD <- sd(pistonrings$diameter[pistonrings$trial])
x <- pistonrings$diameter[!pistonrings$trial]

## UI function
ui <- fluidPage(
  plotOutput("plot"),
  sliderInput("x", "x SD:",
    min=0, max=5, value=0, step=0.1,
    animate=animationOptions(100)
  )
)

# Server logic
server <- function(input, output) {
  output$plot <- renderPlot({
    Main <- paste("Shewhart quality control chart",
        "diameter of piston rings", sprintf("+/- %.1f SD", input$x),
        sep="\n")
    iv <- mu + input$x * c(-SD, SD)
    plot(x, pch = 19, col = x %)(% iv +1, type = "b",
        ylim = mu + 5 * c(-SD, SD), main = Main)
    abline(h = mu)
    abline(h = iv, lty = 2)
  })
}

## Run shiny app
if (interactive()) shinyApp(ui, server)

regular slider

The second example uses range slider returning two values, which is our interval. To spice things up a bit, we combine intervals on two axes to color some random points. The next range slider defines a distance interval and colors the random points inside the ring.

library(shiny)
library(intrval)

set.seed(1)
n <- 10^4
x <- round(runif(n, -2, 2), 2)
y <- round(runif(n, -2, 2), 2)
d <- round(sqrt(x^2 + y^2), 2)

## UI function
ui <- fluidPage(
  titlePanel("intrval example with shiny"),
  sidebarLayout(
    sidebarPanel(
      sliderInput("bb_x", "x value:",
        min=min(x), max=max(x), value=range(x),
        step=round(diff(range(x))/20, 1), animate=TRUE
      ),
      sliderInput("bb_y", "y value:",
        min = min(y), max = max(y), value = range(y),
        step=round(diff(range(y))/20, 1), animate=TRUE
      ),
      sliderInput("bb_d", "radial distance:",
        min = 0, max = max(d), value = c(0, max(d)/2),
        step=round(max(d)/20, 1), animate=TRUE
      )
    ),
    mainPanel(
      plotOutput("plot")
    )
  )
)

# Server logic
server <- function(input, output) {
  output$plot <- renderPlot({
    iv1 <- x %[]% input$bb_x & y %[]% input$bb_y
    iv2 <- x %[]% input$bb_y & y %[]% input$bb_x
    iv3 <- d %()% input$bb_d
    op <- par(mfrow=c(1,2))
    plot(x, y, pch = 19, cex = 0.25, col = iv1 + iv2 + 3,
        main = "Intersecting bounding boxes")
    plot(x, y, pch = 19, cex = 0.25, col = iv3 + 1,
         main = "Deck the halls:\ndistance range from center")  
    par(op)
  })
}

## Run shiny app
if (interactive()) shinyApp(ui, server)

range slider

If you think there are other use cases for intrval in shiny applications, let me know in the comments section!

To leave a comment for the author, please follow the link and comment on their blog: Peter Solymos - R related posts.

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