app.R

#
# This is a Shiny web application. You can run the application by clicking
# the 'Run App' button above.
#
# Find out more about building applications with Shiny here:
#
#    https://shiny.posit.co/
#

library(shiny)
library(dplyr)
library(data.table)
library(xgboost)
library(caret)
# Define UI for application that draws a histogram
ui <- fluidPage(

    # Application title
    titlePanel("TimStuff Fastball Calculator"),

    # Sidebar with a slider input for number of bins 
    sidebarLayout(
        sidebarPanel(
            selectInput("phand",
                        "Hand",
                        c("R","L")),
            numericInput("velo",
                        "Velocity /mph",90),
            numericInput("ivb",
                         "Induced Vertical Break (IVB) /in. (IVB)",16),
            numericInput("hb",
                         "Horizontal Break (HB) /in. (Pitcher's Perspective)",6),
            numericInput("spinrate",
                         "Spin Rate /rpm",2300),
            numericInput("ext",
                         "Extension /ft",6),
            numericInput("spinaxisdiff",
                         "Spin Axis Difference (-180 - 180) /degrees",0),
            numericInput("x0","Horizntal Release Point /ft. (Batter's Perspective)",0),
            numericInput("z0","Vertical Release Point /ft. (Batter's Perspective)", 0),
            
            
        ),

        # Show a plot of the generated distribution
        mainPanel(
           textOutput("distPlot")
        )
    )
)

# Define server logic required to draw a histogram
server <- function(input, output) {

    output$distPlot <- renderText({
       data <- as.data.frame(5)
       setnames(data,"5","start_speed")
       data$start_speed <- input$velo
       data$IVB <- input$ivb
       if(input$phand == "L"){
         data$HB <- input$hb * -1
       }
       else{
       data$HB <- input$hb
       }
       data$EAA <- input$ext / 6.3
       if(input$phand == "L"){
         data$x0 <- input$x0 * -1
       }
       else{
         data$x0 <- input$x0
       }
       data$z0 <- input$z0
       data$spin_rate <- input$spinrate
       data$SADiff <- input$spinaxisdiff
       
       data <- as.matrix(data)
       FBMod <- xgb.load('FB.Model')
       prediction <-predict(FBMod,data)
       TimStuff <- (50 - (prediction - -0.0004397118)/ 0.2180433 * 10)
       # FBMod <- xgb.load("FB.model")
       # vip(FBMod)
       return(TimStuff)
    })
}

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