Prime Factorization Visualization in R and Shiny

server.R

library(shiny)
library(gmp)

drawStar <- function(center, length, pts, direction=0, segments=F, colour=F) {
  if(length(pts)==0) return()
  if(segments & (pts[1]==2)) direction <- direction + pi/2
  for(i in 1:pts[1]) {
    point <- center + 
      length*c(cos(direction+pi/2+i*2*pi/pts[1]),
               sin(direction+pi/2+i*2*pi/pts[1]))    
    if(!segments) {
      if(length(pts)==1)
        if(colour) {
          points(x=point[1], y=point[2],pch=20,col=rainbow(pts[1])[i])
        } else {
          points(x=point[1], y=point[2],pch=20)
        }
      nextdirection <- 0
      if(pts[1]==2) nextdirection <- direction + pi/2
      if(length(pts)>1)
        if((pts[1]!=2)&(pts[2]==2)) nextdirection <- direction+i*2*pi/pts[1]
    } else {
      if(colour) {
        lines(x=c(center[1], point[1]), y=c(center[2], point[2]),col=rainbow(10)[pts[1]%%10],lwd=2)
      } else {
        lines(x=c(center[1], point[1]), y=c(center[2], point[2]))
      }
      nextdirection <- direction + i*2*pi/pts[1]
    }    
    drawStar(center=point, length=length/((pts[1])^(1/1.25)), pts=pts[-1],
             direction=nextdirection, segments=segments, colour=colour)
  }
}

makePFV <- function(N, segments=F, colour=F, direction=0, order='desc') {
  plot(x=c(-1.5,1.5),y=c(1.5,-1.5),pch='',xlab='',ylab='',asp=1, bty='n',axes=F)
  primes <- switch(order,
                   asc=as.numeric(factorize(N)),
                   desc=rev(as.numeric(factorize(N))),
                   rand=sample(as.numeric(factorize(N))))
  drawStar(center=c(0,0),length=1,direction=direction,pts=primes,segments=segments,colour=colour)
}

shinyServer(function(input, output) {

  output$caption <- reactiveText(function() {
    paste(input$N,'=',paste(as.numeric(factorize(input$N)),collapse='x'))
  })
  
  output$visuPlot <- reactivePlot(function() {
    makePFV(N=input$N,
            segments=ifelse(input$segments=='yes',T,F),
            colour=ifelse(input$colour=='yes',T,F),
            direction=input$direction*2*pi/360)    
  })
})

ui.R

library(shiny)

# Define UI for application that plots random distributions 
shinyUI(pageWithSidebar(
  
  # Application title
  headerPanel("Prime Factorization Visualization"),
  
  # Sidebar with a slider input for number of observations
  sidebarPanel(
    
    numericInput("N", "Number to visualize:", 2*3*3*7),
    
    radioButtons("colour", "Colours?",
                 list("Yes" = 'yes',
                      "No" = 'no')),
    
    radioButtons("segments", "Segments?",
                 list("Yes" = 'yes',
                      "No" = 'no')),
    
    sliderInput("direction", 
                "Orientation:", 
                min = -360, 
                max = 360, 
                value = 0)
  ),
  
  # Show a plot of the generated distribution
  mainPanel(
    h3(textOutput("caption")),
    
    plotOutput("visuPlot")
  )
))