Shiny app for displaying baseball history

app.R

library(shiny)

# Define UI for application that draws a histogram
ui <- shinyUI(pageWithSidebar(
  
  # Application title
  headerPanel("Offensive Production in Baseball History"),
  
  # Sidebar with controls to select the variable to plot against year
  # also choose plotting and smooth colors, range of years, and smoothing width
  sidebarPanel(
    selectInput("variable", "Variable:",
                c("Runs" = "R",
                     "Hits" = "H",
                     "Home Runs" = "HR",
                     "Doubles" = "X2B",
                     "Triples" = "X3B",
                     "Walks" = "BB",
                     "Strikeouts" = "SO",
                     "Stolen Bases" = "SB",
                     "Errors" = "E")),
    selectInput("pcolor", "Points Color:",
                c("Blue" = "blue", "Red" = "red", "Green" = "green",
                  "Orange" = "orange", "Black" = "black", "Yellow" = "yellow")),
    selectInput("scolor", "Smooth Color:",
                c("Red" = "red", "Blue" = "blue", "Green" = "green",
                  "Orange" = "orange", "Black" = "black", "Yellow" = "yellow")),
    sliderInput("salpha", "Alpha:",
                min = 0, max = 1, 
                value = 0.5, step = 0.05),
    sliderInput("range", "Range:",
                min = 1901, max = 2016, sep = "",
                value = c(1901, 2016), step = 1),
    sliderInput("decimal", "Loess Smoothing Fraction:",
                min = 0.05, max = 0.95, value = 0.2, step= 0.05)
  ),
  
  # Show the caption and plot of the requested variable against mpg
  mainPanel(
    h3(textOutput("caption")),
    
    plotOutput("mpgPlot")
  )
))

library(Lahman)
library(ggplot2)

# Define server logic required to draw a histogram
server <- 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({
    paste("Variable:", input$variable,
          "Per Game Per Team:",
          input$range[1], "to", input$range[2])
  })
  
  # Return the formula text for printing as a caption
  output$caption <- renderText({
    formulaText()
  })
  
  # Generate a plot of the requested variable against mpg and only 
  # include outliers if requested
  output$mpgPlot <- renderPlot({
    Teams.recent <- subset(Teams, yearID >= input$range[1] &
                             yearID <= input$range[2])
    Teams.recent$stat.game <- Teams.recent[, input$variable] / Teams.recent[, "G"]
    print(ggplot(Teams.recent, aes(yearID, stat.game)) + 
            geom_point(color = input$pcolor, alpha = input$salpha) +
            geom_smooth(size=2, color=input$scolor, method="loess", 
                        span=input$decimal) + 
            xlab("YEAR") + ylab("RATE PER GAME PER TEAM") +
            theme(text = element_text(size=20))
    )
  }, width=600, height=500)
}

# Run the application 
shinyApp(ui = ui, server = server)