In guga31bb/ngscleanR: Helper Functions for Cleaning Player Tracking Data

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.width=9, 
  fig.height=5,
  tidy = 'styler'
)

library(ngscleanR)
library(tidyverse)
library(patchwork)

Load sample week

tracking <- readRDS("../data-raw/sample_bdb_2021.rds")
str(tracking)

labs <- readRDS("../data-raw/coverages_week1.rds") %>%
  mutate(play = paste0(gameId, "_", playId)) %>%
  select(play, coverage)
str(labs)

The main function

This will clean up the data, attach some information associated with the play, and make everything face from left ot right.

cleaned <- tracking %>%
  clean_and_rotate() %>%
  inner_join(labs, by = "play")

str(cleaned)

Play cutting function

This discards any plays where the throw happens before frame 25 (i.e. 1.5 seconds after snap).

cleaned <- cleaned %>%
  cut_plays(
    # get rid of plays with throw before this frame
    throw_frame = 25,
    # get rid of frames that happen after this many frames after pass released
    time_after_event = 10
    )

Plot some sample plays

ex <- sample(cleaned$play, 4)

plots <- map(ex, ~{
  lab <- cleaned %>% filter(play == .x) %>% dplyr::pull(coverage)
  plot <- cleaned %>%
    filter(frame_id == 28, play == .x) %>%
    plot_play(
      animated = FALSE,
      segment_length = 6,
      segment_size = 3,
      dot_size = 4

    )

  plot + 
    labs(title = lab) +
    theme(plot.title = element_blank(),
          plot.caption = element_blank(),
          plot.margin = unit(c(0, 0, 0, 0), "cm")
  )
})

(plots[[1]] + plots[[2]]) / (plots[[3]] + plots[[4]])

The big cleaning function

prepare_bdb_week(
  week = 1,
  dir = "../../nfl-big-data-bowl-2021/input",
  trim_frame = 25,
  frames_after_throw = 10,
  keep_frames = c(30),
  drop_positions = c("QB")
) %>%
  str()