R/calories_burned.R

In armaanshah96/runner: Aiding runners log, calculate, and visualize relevant and informative data about their running progress.

#' Calculates Calories Burned From Exercise
#' @param age Age of individual of numeric vector.
#' @param heart_rate Heart rate (bpm) of individual of numeric vector.
#' @param weight Weight of individual of numeric vector. In pounds if english units and kilograms if metric units.
#' @param time Time spent running of individual of numeric vector. In minutes.
#' @param gendser "male" for male and "female" for female.
#' @param units  Character vector representing the units convention used for weight. Either "english" or "metric". Default is "english".
#' @return numeric vector representing the BMI of an individual based on their height and weight
#' @examples
#' calories_burned(19, 130, 152, 60, "male", "metric")
#' @export

calories_burned <- function(age, heart_rate, weight, time, gender, units="english") {
  # Check parameter types are correct

  if(class(age) != "numeric") {
    stop("age must be a numeric!")
  }

  if(class(heart_rate) != "numeric") {
    stop("heart rate must be a numeric!")
  }

  if(class(weight) != "numeric") {
    stop("weight must be a numeric!")
  }

  if(class(gender) != "character") {
    stop("gender must be a character!")
  }

  if(class(units) != "character") {
    stop("units must be a character!")
  }
  else{
    units = tolower(units)
    if(units != "english" && units != "metric") {
      stop("units must be either 'english' or 'metric'")
      geterrmessage()
    }
  }

  if(tolower(units) == "english" ){
    if(tolower(gender) == "male"){
      calories = ((age * .2017) - (weight * 0.09036) + (heart_rate * .6309) - 55.0969) * time/4.184
    }
    if(tolower(gender) == "female"){
      calories = ((age * 0.074) - (weight * 0.05741) + (heart_rate * .4472) - 20.4022) * time/4.184
    }
    if(calories <= 0){
      stop("please check to make sure the information is correct")
    }
    return(signif(calories,4))
  }

  # Calories burned formula for metric units
  if(tolower(units) == "metric" ){
    weight = weight * 2.20462
    if(tolower(gender) == "male"){
      calories = ((age * .2017) - (weight * 0.09036) + (heart_rate * .6309) - 55.0969) * time/4.184
    }
    if(tolower(gender) == "female"){
      calories = ((age * 0.074) - (weight * 0.05741) + (heart_rate * .4472) - 20.4022) * time/4.184
    }
    if(calories <= 0){
      stop("please check to make sure the information is correct")
    }
    return(signif(calories,4))
  }
}