R/helper_add_cp_cpoe.R

In nflfastR: Functions to Efficiently Access NFL Play by Play Data

################################################################################
# Author: Ben Baldwin, Sebastian Carl
# Purpose: Function to add cp and cpoe variables.
# CP model created by Zach Feldman: https://github.com/z-feldman/Expected_Completion_NFL
# Code Style Guide: styler::tidyverse_style()
################################################################################

add_cp <- function(pbp) {

  # testing only
  # pbp <- g

  passes <- prepare_cp_data(pbp)

  if (!nrow(passes %>% dplyr::filter(.data$valid_pass == 1)) == 0) {
    pred <- stats::predict(fastrmodels::cp_model, as.matrix(passes %>% dplyr::select(-"complete_pass", -"valid_pass"))) %>%
      tibble::as_tibble() %>%
      dplyr::rename(cp = "value") %>%
      dplyr::bind_cols(passes) %>%
      dplyr::select("cp", "valid_pass")

    pbp <- pbp %>%
      dplyr::bind_cols(pred) %>%
      dplyr::mutate(
        cp = dplyr::if_else(
          .data$valid_pass == 1, .data$cp, NA_real_
        ),
        cpoe = dplyr::if_else(!is.na(.data$cp), 100 * (.data$complete_pass - .data$cp), NA_real_)
      ) %>%
      dplyr::select(-"valid_pass")

    user_message("added cp and cpoe", "done")
  } else {
    pbp <- pbp %>%
      dplyr::mutate(
        cp = NA_real_,
        cpoe = NA_real_
      )
    user_message("No non-NA values for cp calculation detected. cp and cpoe set to NA", "info")
  }

  return(pbp)
}


### helper function for getting the data ready
prepare_cp_data <- function(pbp) {

  # valid pass play: at least -15 air yards, less than 70 air yards, has intended receiver, has pass location
  passes <- pbp %>%
    dplyr::mutate(
      receiver_player_name =
        stringr::str_extract(.data$desc, "(?<=((to)|(for))\\s[:digit:]{0,2}\\-{0,1})[A-Z][A-z]*\\.\\s?[A-Z][A-z]+(\\s(I{2,3})|(IV))?"),
      pass_middle = dplyr::if_else(.data$pass_location == "middle", 1, 0),
      air_is_zero = dplyr::if_else(.data$air_yards == 0, 1, 0),
      distance_to_sticks = .data$air_yards - .data$ydstogo,
      valid_pass = dplyr::if_else(
        (.data$complete_pass == 1 | .data$incomplete_pass == 1 | .data$interception == 1) &
          !is.na(.data$air_yards) & .data$air_yards >= -15 & .data$air_yards < 70 &
          (!is.na(.data$receiver_player_name) | !is.na(.data$receiver_player_id)) & !is.na(.data$pass_location),
        1, 0
      )
    ) %>%
    dplyr::select(
      "complete_pass", "air_yards", "yardline_100", "ydstogo",
      "down1", "down2", "down3", "down4", "air_is_zero", "pass_middle",
      "era2", "era3", "era4", "qb_hit", "home",
      "outdoors", "retractable", "dome", "distance_to_sticks", "valid_pass"
    )
}