R/econ.R

In farfallawang/mosaicApps: A toolkit for teaching applied math and stats

#' Interactive applet to explore integrals as applied to economics
#' 
#' An applet applying integrals to the economic concepts of supply and demand.
#' 
#' Two splines are created from the sliders. The first points of the spline are
#' anchored at x=0, y=0 for the supply spline, and x=0, y=50 for the demand
#' spline. The sliders allow the user to manipulate the y points which
#' determine the splines at x=10 and x=20. The area between the equilibrium
#' point and the splines is shaded. In perfect competition, the area above the
#' supply spline and below the equilibrium point is the producer surplus, and
#' the area below the demand spline and above the equilibrium point is the
#' consumer surplus.
#' 
#' Known bugs: If the curves do not intersect as may happen when demand pt. 2
#' is high and supply pt. 2 is low, there will be an error: Error in
#' uniroot(func, interval = c(0, 20)) : f() values at end points not of
#' opposite sign However it's better for the exercise to be more flexible than
#' less.
#' 
#' @author Andrew Rich (\email{andrew.joseph.rich@@gmail.com}) 
#' , Daniel Kaplan (\email{kaplan@@macalester.edu})
#' , Mengdie Wang(\email{mwang3@@macalester.edu})
#' and Jingjing Yang(\email{jyang1@@macalester.edu})
#' @keywords economics
#' @examples
#' econApp() #if you do not want to display the code
#' econApp(display = "showcase") #if you want to display the code

#' @export
econApp <- function(display = c("normal","showcase")){
  display = match.arg(display)
  appDir <- system.file("shinyApps","econ",package = "mosaicApps")
  if (appDir == ""){
    stop("Couldn't find example directory. Try reinstalling `mosaicApps`.",
         call. = FALSE)
  }
  shiny::runApp(appDir, display.mode = display)
}