Overview:

This project is designed to help users track their bodyweight via a google sheet and build an app using Shiny that updates in real time and visualizes weightloss progress. Checkout Part 2 of this project which includes a predictive model to help users identify target caloric intake during dieting, maintenance, and massing phases.

Steps

1. Create a google sheet

• Name sheet “Bodyweight Tracker”

2. Create Shiny App

Shiny App Code

Load the necessary R Packages:

# Define list of required packages
packages<-c("shiny", "googlesheets","DT","ggplot2","ggplot2", "dplyr")
#logical vector that lists which packages are already installed
packages_checked<-(packages %in% installed.packages()[,1])
#list of packages that are not installed
packages_required <- packages[!packages_checked]
#install packages that are required
if (sum(!(packages_checked))>0) {  
  install.packages(packages_required)
}
#load packages
"getSymbols.warning4.0"=FALSE
lapply(packages, require, character.only= TRUE)
rm(packages,packages_checked, packages_required)

Create Google Sheet object:

bodyweight_sheet <- gs_url("https://docs.google.com/spreadsheets/d/YOURAPIKEY/edit?usp=sharing")

bodyweight_table <- gs_read(bodyweight_sheet)

Define Server Logic:

server<- (function(input, output, session) {
  
  #Table of raw data
  output$the_data <- renderDataTable({
    
    datatable(bodyweight_table)
    
  })
  
  
  #Time series plot of bodyweight
  output$the_graph <- renderPlot({
    
    ggplot(data = bodyweight_table, aes(x = as.Date(bodyweight_table$Date, "%m/%d/%Y"), y = bodyweight_table$Bodyweight)) +
      geom_point(color="red")+
      geom_line()+
      stat_smooth(method="auto")+ 
      labs(x = "Date", y="Bodyweight (lbs)")
    
  })
  

    #Time series plot of weekly bodyweight rate of change  
  output$weekly_loss <- renderPlot({
    
    ggplot(data = bodyweight_table, aes(x = as.Date(bodyweight_table$Date, "%m/%d/%Y"), y = bodyweight_table$Weekly_Rate)) +
      geom_point(color="red")+
      geom_line()+
      geom_hline(yintercept=-.02, linetype="dashed", color = "red", size=2)+
      geom_hline(yintercept=-.01, linetype="dashed", color = "red", size=2)+
      stat_smooth(method="auto")+ 
      labs(x = "Date", y="Percent Bodyweight Change Per Week")
    
  })
  
  
  #Tooltip functionality
  output$info <- renderText({
    paste0("x=", input$plot_click$x, "\ny=", input$plot_click$y)
  })
  
})

Define UI Layout:

ui<-(
  fluidPage(
    titlePanel("Bodyweight Tracker"),
    sidebarLayout(
      sidebarPanel(
        tags$a(href="Hyperlink to your Google Sheet", "Click for raw data")
      ),
      mainPanel(
        tabsetPanel(type = "tabs",
                    tabPanel("Daily Bodyweight", plotOutput("the_graph", click = "plot_click"),verbatimTextOutput("info")),
                    tabPanel("Weekly Change", plotOutput("weekly_loss")),
                    tabPanel("Raw Data", dataTableOutput("the_data"))
        )
      )
    )
  ))


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