R/cumulative_miles_by_id.R

In jarad/mileageClub: Provides functions and data for the Mary Greeley Medical Center Mileage Club

#' Calculate cumulative miles for each individual by week
#' 
#' For each individual, calculate the miles run that week and the 
#' cumulative miles run up to and including that week.
#' 
#' @param d A \code{data.frame} containing all the card and day information.
#' @param miles_per_card An integer specifying how many miles a card is worth.
#' @return A \code{data.frame} with the cumulative miles for each individual by week.
#' @import dplyr
#' @export
#' @examples 
#' \dontrun{
#' read_cards() %>% cumulative_miles_by_id
#' }
cumulative_miles_by_id = function(d, miles_per_card=5) {
  d %>% 
    group_by_(~id) %>%
    arrange_(~week) %>%
    mutate_(one = 1, 
            cumulative_miles = ~miles_per_card*cumsum(one)) %>%
    select_(~ -one)
}