Shiny application to graph batting trajectories of baseball sluggers

server.R

library(shiny)
library(Lahman)
library(ggplot2)

# preliminary work
Master$birthyear <- with(Master, 
                         ifelse(birthMonth >= 7, birthYear + 1, birthYear))
Batting <- merge(Batting, 
                 Master[, c("playerID", "nameFirst", "nameLast", "birthyear")],
                 by="playerID")
Batting$Age <- with(Batting, yearID - birthyear)

# Define server logic required to plot various variables against year
shinyServer(function(input, output) {
  
  # Compute the forumla text in a reactive function since it is 
  # shared by the output$caption and output$mpgPlot functions
  formulaText <- reactive({
    L <- subset(Master, playerID==input$player)$nameLast
    F <- subset(Master, playerID==input$player)$nameFirst
    paste(input$variable, "Trajectory of ", paste(F, L))
  })
  
  output$caption <- renderText({
    formulaText()
  })
  
  output$mpgPlot <- renderPlot({
    d <- subset(Batting, playerID==input$player)
    d$stat <- d[, input$variable] / d[, "AB"]
    myplot <- ggplot(d, aes(Age, stat)) + 
      geom_point(size=5, color="red") + 
      ylab(paste(input$variable, "RATE")) +
      theme(axis.text = element_text(size = rel(2))) + 
      theme(axis.title = element_text(size = rel(3)))
    if(input$smooth=="loess") 
         myplot <- myplot + geom_smooth(size=3, method="loess") else
         myplot <- myplot + 
               stat_smooth(method = "lm", size = 3, formula = y ~ x + I(x ^ 2))
    print(myplot) 
  }, width=600, height=500)
})

ui.R

library(shiny)

shinyUI(pageWithSidebar(
  
  # Application title
  headerPanel("Career Trajectories of 500 Home Run Club"),
  
  # Sidebar with controls to select the variable to plot against mpg
  # and to specify whether outliers should be included
  sidebarPanel(
    selectInput("player", "Player:",
                list("Hank Aaron" = "aaronha01",
                     "Ernie Banks" = "bankser01",
                     "Barry Bonds" = "bondsba01", 
                     "Jimmie Foxx" = "foxxji01",
                     "Ken Griffey Jr" = "griffke02", 
                     "Reggie Jackson" = "jacksre01",
                     "Harmon Killebrew" = "killeha01",
                     "Mickey Mantle" = "mantlmi01",
                     "Eddie Mathews" = "matheed01",
                     "Willie Mays" = "mayswi01",
                     "Willie McCovey" = "mccovwi01",
                     "Mark McGwire" = "mcgwima01",
                     "Eddie Murray" = "murraed02",
                     "Mel Ott" = "ottme01",
                     "Rafael Palmeiro" = "palmera01",
                     "Manny Ramirez" = "ramirma02",
                     "Frank Robinson" = "robinfr02",
                     "Alex Rodriguez" = "rodrial01",         
                     "Babe Ruth" = "ruthba01",
                     "Mike Schmidt" = "schmimi01",
                     "Gary Sheffield" = "sheffga01",
                     "Sammy Sosa" = "sosasa01",
                     "Frank Thomas" = "thomafr04",
                     "Jim Thome" = "thomeji01",
                     "Ted Williams" = "willite01")),
    selectInput("variable", "Variable:",
                list("Home Run Rate" = "HR",
                     "Batting Average" = "H", 
                     "Strikeout Rate" = "SO",
                     "Doubles Rate" = "X2B",
                     "Triples Rate" = "X3B",
                     "Walk Rate" = "BB")),
    radioButtons("smooth", "Smoothing type:",
                 list("Loess" = "loess",
                      "Quadratic" = "lm"))
  ),
  
  # Show the caption and plot of the requested variable against mpg
  mainPanel(
    h3(textOutput("caption")),
    
    plotOutput("mpgPlot")
  )
))