Using R/fitzRoy to ask: how many times a V/AFL team with the same lineup has played together?

If you sit in the intersection of “likes Australian Rules football / finds sport statistics interesting / is on Twitter”, you’ve probably come across Swamp. One of his recent tweets tells us that:

You may go on to ask: has any team lineup from one of the almost 16 000 recorded games played together again in another game? And if so, how often?

The answer to that question is at once surprising, less surprising when you think about it, and quite easy to figure out using the ever-helpful fitzRoy package.

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Debuting in a VFL/AFL Grand Final is rare

When Marlion Pickett runs onto the M.C.G for Richmond in the AFL Grand Final this Saturday, he’ll be only the sixth player in 124 finals to debut on the big day.

The sole purpose of this blog post is to illustrate how incredibly easy it is to figure this out, thanks to the dplyr and fitzRoy packages.

library(dplyr)
library(fitzRoy)

afldata <- get_afltables_stats()

afldata %>% 
  select(Season, Round, Date, ID, First.name, Surname, Playing.for, 
         Home.team, Home.score, Away.team, Away.score) %>% 
  group_by(ID) %>% 
  arrange(Date) %>%
  # a player's first game 
  slice(1) %>% 
  ungroup() %>% 
  # grand finals only
  filter(Round == "GF") %>%
  # get the winning/losing margin 
  mutate(Margin = case_when(Playing.for == Home.team ~ Home.score - Away.score,
                            TRUE ~ Away.score - Home.score)) %>% 
  select(-Home.team, -Away.team, -Home.score, -Away.score)
Season Round Date ID First.name Surname Playing.for Margin
1908 GF 1908-09-26 5573 Harry Prout Essendon -9
1920 GF 1920-10-02 6677 Billy James Richmond 17
1923 GF 1923-10-20 6915 George Rawle Essendon 17
1926 GF 1926-10-09 3824 Francis Vine Melbourne 57
1952 GF 1952-09-27 9361 Keith Batchelor Collingwood -46

How long since your team scored 100+ points? This blog’s first foray into the fitzRoy R package

When this blog moved from bioinformatics to data science I ran a Twitter poll to ask whether I should start afresh at a new site or continue here. “Continue here”, you said.

So let’s test the tolerance of the long-time audience and celebrate the start of the 2019 season as we venture into the world of – Australian football (AFL) statistics!
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