Joining Betting Data

June 26, 2018
By

(This article was first published on Analysis of AFL, and kindly contributed to R-bloggers)

This example will be using Betfair which we hope to add to fitzRoy in the future. Making it easier to compare Squiggle and maybe your own models vs the market!

Step One Read in the Betfair Data

The first step is just go to the betfair site and download the AFL file with the data we need.

I will only be joining the 2017-onwards data because that’s what squiggle has!

library(readxl)
library(tidyverse)
## ── Attaching packages ───────────────────────────────────────────────────────── tidyverse 1.2.1 ──
## ✔ ggplot2 3.1.0     ✔ purrr   0.2.5
## ✔ tibble  2.0.1     ✔ dplyr   0.7.8
## ✔ tidyr   0.8.2     ✔ stringr 1.3.1
## ✔ readr   1.3.1     ✔ forcats 0.3.0
## ── Conflicts ──────────────────────────────────────────────────────────── tidyverse_conflicts() ──
## ✖ dplyr::filter() masks stats::filter()
## ✖ dplyr::lag()    masks stats::lag()
filetodownload <- "https://www.betfair.com.au/hub/wp-content/uploads/sites/2/2018/10/Copy-of-Weekly-AFL-Data-Dump-2017-YTD-2.xlsx"
download.file(filetodownload,"aflodds.xlsx",mode="wb")

Copy_of_Weekly_AFL_Data_Dump_2017_YTD <- read_excel("aflodds.xlsx", 
    col_types = c("date", "text", "numeric", 
         "text", "text", "text", "text", "numeric", 
        "text", "text", "text", "text", "text", 
         "text", "text", "text"))
## Warning in read_fun(path = enc2native(normalizePath(path)), sheet_i =
## sheet, : Expecting date in B4 / R4C2: got 'SETT_DATE'
## New names:
## * `` -> `..1`
## * `` -> `..2`
## * `` -> `..4`
## * `` -> `..5`
## * `` -> `..6`
## * … and 10 more
dim(Copy_of_Weekly_AFL_Data_Dump_2017_YTD)
## [1] 1610   16
head(Copy_of_Weekly_AFL_Data_Dump_2017_YTD)
## # A tibble: 6 x 16
##   ..1                 ..2   `AFL 2017 - YTD` ..4   ..5   ..6   ..7     ..8
##                                  
## 1 NA                                  NA            NA
## 2 NA                  EVEN…               NA MENU… EVEN… PATHS PARE…    NA
## 3 2017-03-23 00:00:00 1281…               NA AFL … Matc… AFL … Aust…    NA
## 4 2017-03-23 00:00:00 1281…               NA AFL … Matc… AFL … Aust…    NA
## 5 2017-03-23 00:00:00 1281…               NA AFL … Matc… AFL … Aust…    NA
## 6 2017-03-23 00:00:00 1281…               NA AFL … Matc… AFL … Aust…    NA
## # … with 8 more variables: ..9 , ..10 , ..11 , ..12 ,
## #   ..13 , ..14 , ..15 , ..16 
df_bookie<-slice(Copy_of_Weekly_AFL_Data_Dump_2017_YTD,2:1430)
names(df_bookie) <- lapply(df_bookie[1, ], as.character)
## Warning: Must use a character vector as names.
## This warning is displayed once per session.
names(df_bookie)
##  [1] NA                   "EVENT_ID"           NA                  
##  [4] "MENU_HINT"          "EVENT_NAME"         "PATHS"             
##  [7] "PARENT_MENU_HINT"   NA                   "PARENT_EVENT_NAME" 
## [10] "SELECTION_NAME"     "INPLAY"             "MIN_PRICE"         
## [13] "MAX_PRICE"          "LAST_MATCHED_PRICE" "WAP"               
## [16] "VOLUME_AUD"

The columns of interest to join on would be, the Date, the selection name and WAP and we want to maybe join this on to the squiggle guys. The next thing we notice by viewing the dataset View(Copy_of_Weekly_AFL_Data_Dump_2017_YTD) is that if we look at the column INPLAY we want when it is N the reason being is that we want to compare the squiggle pre game tips with what the market was doing pre game.

Step Two Get the squiggle data

library(fitzRoy)
tips <- get_squiggle_data("tips")
## Getting data from https://api.squiggle.com.au/?q=tips
df<-tips%>%mutate(home.margin=ifelse(hteam==tip, margin,-margin))%>%
  mutate(away.margin=ifelse(ateam==tip, margin,-margin)) %>%
  select(source,date,correct,  hconfidence,hteam,
         ateam,home.margin,away.margin,err ,tip,round, year)
 

df1<-select(df,source, date, correct, hconfidence,hteam, home.margin, err, tip, round, year )
df1$H_A<-"HOME"
df2<-select(df, source, date, correct, hconfidence, ateam, away.margin, err, tip, round, year)
df2$H_A<-"AWAY"
colnames(df1)[5]<-"Team"

colnames(df1)[6] <- "margin"

colnames(df2)[5]<-"Team"

colnames(df2)[6]<-"margin"

df3<-rbind(df1,df2)
colnames(df3)[2]<-"Date"

Step Three make sure the names of columns align!

colnames(df_bookie)[1] <- "Date"
colnames(df_bookie)[10] <- "Team"
colnames(df_bookie)[3]<-"x3"
colnames(df_bookie)[8]<-"x8"
df_bookie<-df_bookie%>%filter(INPLAY=="N")%>%
  select(Date, Team, WAP)
df_bookie$Date<-as.Date(df_bookie$Date)
df3$Date<-as.Date(df3$Date)

Step 4 Check what you are joining by!

Before we join on the datasets, we need to make sure that our IDs line up, so that our teams are named the same in both datasets.

unique(df_bookie$Team)
##   [1] "Carlton"                   "Richmond"                 
##   [3] "Carlton +14.5pts"          "Richmond -14.5pts"        
##   [5] "Collingwood +14.5pts"      "Western Bulldogs -14.5pts"
##   [7] "Fremantle"                 "Geelong Cats"             
##   [9] "Fremantle +8.5pts"         "Geelong -8.5pts"          
##  [11] "Sydney Swans"              "Western Bulldogs"         
##  [13] "Sydney +22.5pts"           "Western Bulldogs -22.5pts"
##  [15] "Adelaide Crows"            "Hawthorn"                 
##  [17] "Brisbane Lions"            "Essendon"                 
##  [19] "Brisbane +15.5pts"         "Essendon -15.5pts"        
##  [21] "St Kilda +38.5pts"         "West Coast -38.5pts"      
##  [23] "North Melbourne"           "Melbourne Demons"         
##  [25] "Carlton +29.5pts"          "Melbourne -29.5pts"       
##  [27] "Fremantle +28.5pts"        "Port Adelaide -28.5pts"   
##  [29] "Collingwood"               "Collingwood +12.5pts"     
##  [31] "Sydney -12.5pts"           "West Coast Eagles"        
##  [33] "Richmond +12.5pts"         "West Coast -12.5pts"      
##  [35] "Adelaide -8.5pts"          "Port Adelaide +8.5pts"    
##  [37] "St Kilda"                  "Carlton +17.5pts"         
##  [39] "Essendon -17.5pts"         "Gold Coast Suns"          
##  [41] "Gold Coast +20.5pts"       "Hawthorn -20.5pts"        
##  [43] "Sydney +20.5pts"           "West Coast -20.5pts"      
##  [45] "North Melbourne +23.5pts"  "Western Bulldogs -23.5pts"
##  [47] "Fremantle +22.5pts"        "Melbourne -22.5pts"       
##  [49] "GWS Giants"                "Port Adelaide Power"      
##  [51] "GWS -17.5pts"              "Port Adelaide +17.5pts"   
##  [53] "Adelaide -35.5pts"         "Essendon +35.5pts"        
##  [55] "Collingwood -6.5pts"       "St Kilda +6.5pts"         
##  [57] "Brisbane +17.5pts"         "Richmond -17.5pts"        
##  [59] "Geelong -14.5pts"          "Hawthorn +14.5pts"        
##  [61] "Carlton +52.5pts"          "Port Adelaide -52.5pts"   
##  [63] "Adelaide -27.5pts"         "Gold Coast +27.5pts"      
##  [65] "GWS -13.5pts"              "Sydney +13.5pts"          
##  [67] "Fremantle -6.5pts"         "North Melbourne +6.5pts"  
##  [69] "Geelong -15.5pts"          "St Kilda +15.5pts"        
##  [71] "Hawthorn +16.5pts"         "West Coast -16.5pts"      
##  [73] "Melbourne +5.5pts"         "Richmond -5.5pts"         
##  [75] "GWS -24.5pts"              "Western Bulldogs +24.5pts"
##  [77] "Carlton +30.5pts"          "Sydney -30.5pts"          
##  [79] "Brisbane +40.5pts"         "Port Adelaide -40.5pts"   
##  [81] "Gold Coast +14.5pts"       "North Melbourne -14.5pts" 
##  [83] "Fremantle +25.5pts"        "West Coast -25.5pts"      
##  [85] "Collingwood +26.5pts"      "Geelong -26.5pts"         
##  [87] "Adelaide -39.5pts"         "Richmond +39.5pts"        
##  [89] "GWS -14.5pts"              "St Kilda +14.5pts"        
##  [91] "Adelaide -37.5pts"         "North Melbourne +37.5pts" 
##  [93] "Geelong -16.5pts"          "Gold Coast +16.5pts"      
##  [95] "Richmond +26.5pts"         "Western Bulldogs -26.5pts"
##  [97] "Brisbane +49.5pts"         "Sydney -49.5pts"          
##  [99] "Melbourne -14.5pts"        "Western Bulldogs +16.5pts"
## [101] "Collingwood +31.5pts"      "GWS -31.5pts"             
## [103] "Essendon +27.5pts"         "Geelong -27.5pts"         
## [105] "Adelaide -38.5pts"         "Melbourne +38.5pts"       
## [107] "North Melbourne -7.5pts"   "Sydney +7.5pts"           
## [109] "Port Adelaide -27.5pts"    "Wetsern Bulldogs"         
## [111] "Geelong +3.5pts"           "Western Bulldogs -3.5pts" 
## [113] "Collingwood -12.5pts"      "Hawthorn +12.5pts"        
## [115] "Essendon +11.5pts"         "West Coast -11.5pts"      
## [117] "Geelong -9.5pts"           "Port Adelaide +9.5pts"    
## [119] "Hawthorn +40.5pts"         "Sydney -40.5pts"          
## [121] "St Kilda +15.5"            "Western Bulldogs -15.5pts"
## [123] "Essendon +4.5pts"          "Richmond -4.5pts"         
## [125] "Fremantle +35.5pts"        "Brisbane +51.5pts"        
## [127] "Collingwood -51.5pts"      "Carlton +21.5pts"         
## [129] "North Melbourne -21.5pts"  "GWS +12.5pts"             
## [131] "Hawthorn +42.5pts"         "Port Adelaide -42.5pts"   
## [133] "Adelaide -6.5pts"          "Geelong +6.5pts"          
## [135] "Gold Coast +8.5pts"        "West Coast -8.5pts"       
## [137] "Essendon +29.5pts"         "GWS -29.5pts"             
## [139] "Sydney -7.5pts"            "Western Bulldogs +7.5pts" 
## [141] "Adelaide -36.5pts"         "St Kilda +36.5pts"        
## [143] "Essendon +25.5pts"         "Port Adelaide -25.5pts"   
## [145] "Brisbane +7.5pts"          "Fremantle -7.5pts"        
## [147] "Carlton +25.5pts"          "GWS -25.5pts"             
## [149] "Geelong -5.5pts"           "West Coast +5.5pts"       
## [151] "Adelaide -48.5pts"         "Hawthorn +48.5pts"        
## [153] "Fremantle +57.5pts"        "Geelong -57.5pts"         
## [155] "Gold Coast +37.5pts"       "St Kilda -37.5pts"        
## [157] "West Coast +25.5pts"       "Western Bulldogs -25.5pts"
## [159] "Adelaide -24.5pts"         "Carlton +24.5pts"         
## [161] "Gold Coast -10.5pts"       "North Melbourne +10.5pts" 
## [163] "Geelong +21.5pts"          "GWS -21.5pts"             
## [165] "Collingwood -9.5pts"       "Hawthorn +9.5pts"         
## [167] "Fremantle +11.5pts"        "St Kilda -11.5pts"        
## [169] "Brisbane +44.5pts"         "Essendon -44.5pts"        
## [171] "Gold Coast +45.5pts"       "Sydney -45.5pts"          
## [173] "Brisbane +30.5pts"         "Geelong -30.5pts"         
## [175] "Fremantle +16.5pts"        "North Melbourne -16.5pts" 
## [177] "Essendon +5.5pts"          "St Kilda -5.5pts"         
## [179] "North Melbourne +46.5pts"  "Port Adelaide -46.5pts"   
## [181] "Fremantle +26.5pts"        "West Coast -26.5pts"      
## [183] "Essendon -34.5pts"         "North Melbourne +34.5pts" 
## [185] "Melbourne +9.5pts"         "Port Adelaide -9.5pts"    
## [187] "St Kilda +31.5pts"         "Sydney -31.5pts"          
## [189] "Sydney -14.5pts"           "Melbourne -19.5pts"       
## [191] "North Melbourne +19.5pts"  "Port Adelaide -37.5pts"   
## [193] "St Kilda +37.5pts"         "Gold Coast +15.5pts"      
## [195] "Richmond -15.5pts"         "Essendon -5.5pts"         
## [197] "Western Bulldogs +5.5pts"  "Adelaide -12.5pts"        
## [199] "Brisbane +54.5pts"         "West Coast -54.5pts"      
## [201] "Melbourne +13.5pts"        "Carlton +26.5pts"         
## [203] "Essendon -26.5pts"         "Brisbane +29.5pts"        
## [205] "Western Bulldogs -29.5pts" "Collingwood -19.5pts"     
## [207] "Fremantle -12.5pts"        "Gold Coast +12.5pts"      
## [209] "Adelaide -11.5pts"         "Port Adelaide +11.5pts"   
## [211] "GWS -5.5pts"               "Geelong +8.5pts"          
## [213] "Richmond -8.5pts"          "Adelaide -28.5pts"        
## [215] "Essendon +28.5pts"         "Carlton +42.5pts"         
## [217] "West Coast -42.5pts"       "Hawthorn -16.5pts"        
## [219] "North Melbourne +16.5pts"  "Collingwood +22.5pts"     
## [221] "Port Adelaide -22.5pts"    "Sydney +11.5pts"          
## [223] "Essendon -20.5pts"         "Brisbane +45.5pts"        
## [225] "Melbourne -45.5pts"        "Richmond -26.5pts"        
## [227] "Hawthorn +3.5pts"          "Collingwood +20.5pts"     
## [229] "Melbourne -20.5pts"        "Gold Coast +56.5pts"      
## [231] "Port Adelaide -56.5pts"    "Essendon -42.5pts"        
## [233] "Fremantle +42.5pts"        "Adelaide +2.5pts"         
## [235] "West Coast -2.5pts"        "Essendon +37.5pts"        
## [237] "Sydney -37.5pts"           "Geelong +16.5pts"         
## [239] "Sydney -16.5pts"           "GWS -16.5pts"             
## [241] "West Coast +16.5pts"       "GWS +9.5pts"              
## [243] "Richmond -9.5pts"          "Richmond -30.5pts"        
## [245] "Brisbane +24.5pts"         "St Kilda -24.5pts"        
## [247] "Western Bullbogs"          "GWS Giants -17.5pts"      
## [249] "Western Bulldogs +17.5pts" "St Kilda -19.5pts"        
## [251] "Gold Coast"                "Carlton -13.5pts"         
## [253] "Gold Coast +13.5pts"       "Brisbane"                 
## [255] "Melbourne"                 "Brisbane +18.5pts"        
## [257] "Melbourne -18.5pts"        "Essendon -11.5pts"        
## [259] "West Coast"                "Port Adelaide"            
## [261] "Sydney"                    "Port Adelaide +16.5pts"   
## [263] "Geelong"                   "Hawthorn +8.5pts"         
## [265] "Carlton +11.5pts"          "Collingwood -11.5pts"     
## [267] "Melbourne -21.5pts"        "North Melbourne +21.5pts" 
## [269] "Fremantle -11.5pts"        "Gold Coast +11.5pts"      
## [271] "Adelaide"                  "Adelaide -20.5pts"        
## [273] "St Kilda +20.5pts"         "Brisbane +52.5pts"        
## [275] "Adelaide -31.5pts"         "GWS"                      
## [277] "Fremantle +32.5pts"        "GWS -32.5pts"             
## [279] "Brisbane +42.5pts"         "Richmond -42.5pts"        
## [281] "Carlton +13.5pts"          "North Melbourne -13.5pts" 
## [283] "Gold Coast +36.5pts"       "West Coast -36.5pts"      
## [285] "Geelong -29.5pts"          "St Kilda +29.5pts"        
## [287] "Adelaide +26.5pts"         "Sydney -26.5pts"          
## [289] "Carlton +33.5pts"          "West Coast -33.5pts"      
## [291] "Geelong +14.5pts"          "Port Adelaide -14.5pts"   
## [293] "Fremantle -10.5pts"        "Western Bulldogs +10.5pts"
## [295] "Hawthorn -12.5pts"         "North Melbourne +12.5pts" 
## [297] "Brisbane -6.5pts"          "Gold Coast +6.5pts"       
## [299] "Richmond -13.5pts"         "Collingwood -5.5pts"      
## [301] "Western Bulldogs -17.5pts" "Brisbane +38.5pts"        
## [303] "GWS -38.5pts"              "St Kilda +16.5pts"        
## [305] "Adelaide -45.5pts"         "North Melbourne +7.5pts"  
## [307] "Port Adelaide -7.5pts"     "Essendon +3.5pts"         
## [309] "Melbourne -3.5pts"         "Collingwood +13.5pts"     
## [311] "Geelong -17.5pts"          "GWS +17.5pts"             
## [313] "Gold Coast +28.5pts"       "Western Bulldogs -28.5pts"
## [315] "Essendon +13.5pts"         "Hawthorn -13.5pts"        
## [317] "Port Adelaide +4.5pts"     "West Coast -4.5pts"       
## [319] "North Melbourne +29.5pts"  "Sydney -29.5pts"          
## [321] "Adelaide -55.5pts"         "Carlton +55.5pts"         
## [323] "Richmond -35.5pts"         "St Kilda +18.5pts"        
## [325] "Brisbane +22.5pts"         "Collingwood -22.5pts"     
## [327] "Gold Coast +23.5pts"       "Melbourne -23.5pts"       
## [329] "North Melbourne +26.5pts"  "Collingwood +9.5pts"      
## [331] "Adelaide -23.5pts"         "Western Bulldogs +23.5pts"
## [333] "Fremantle +34.5pts"        "Sydney -34.5pts"          
## [335] "Collingwood -25.5pts"      "St Kilda +25.5pts"        
## [337] "GWS +14.5pts"              "Carlton +38.5pts"         
## [339] "Melbourne -38.5pts"        "Hawthorn -15.5pts"        
## [341] "Richmond -2.5pts"          "West Coast +2.5pts"       
## [343] "Richmond -44.5pts"         "St Kilda +44.5pts"        
## [345] "Brisbane +19.5pts"         "Sydney -19.5pts"          
## [347] "Carlton +49.5pts"          "Geelong -49.5pts"         
## [349] "Adelaide +5.5pts"          "Melbourne -5.5pts"        
## [351] "Sydney -52.5pts"           "Melbourne -37.5pts"       
## [353] "Western Bulldogs +37.5pts" "Port Adelaide -3.5pts"    
## [355] "Essendon +22.5pts"         "Richmond -22.5pts"        
## [357] "Brisbane +27.5pts"         "North Melbourne -27.5pts" 
## [359] "Adelaide -21.5pts"         "GWS +21.5pts"             
## [361] "Collingwood -39.5pts"      "Fremantle +39.5pts"       
## [363] "Port Adelaide -6.5pts"     "Richmond +6.5pts"         
## [365] "North Melbourne +15.5pts"  "Gold Coast +46.5pts"      
## [367] "GWS -46.5pts"              "St Kilda +26.5pts"        
## [369] "Fremantle +23.5pts"        "Collingwood +10.5pts"     
## [371] "Melbourne -10.5pts"        "Sydney -13.5pts"          
## [373] "West Coast +13.5pts"       "Carlton +4.5pts"          
## [375] "Fremantle -4.5pts"         "Gold Coast +10.5pts"      
## [377] "St Kilda -10.5pts"         "Adelaide +14.5pts"        
## [379] "Hawthorn -14.5pts"         "Essendon +26.5pts"        
## [381] "Melbourne +7.5pts"         "Brisbane +20.5pts"        
## [383] "GWS -20.5pts"              "Western Bulldogs +27.5pts"
## [385] "Gold Coast +52.5pts"       "Hawthorn -52.5pts"        
## [387] "Carlton +47.5pts"          "Collingwood -47.5pts"     
## [389] "Richmond -12.5pts"         "Sydney +12.5pts"          
## [391] "Geelong -33.5pts"          "Western Bulldogs +33.5pts"
## [393] "Carlton +35.5pts"          "Port Adelaide -35.5pts"   
## [395] "Collingwood -42.5pts"      "Gold Coast +42.5pts"      
## [397] "GWS -8.5pts"               "Adelaide -14.5pts"        
## [399] "West Coast +14.5pts"       "Melbourne -39.5pts"       
## [401] "St Kilda +39.5pts"         "Fremantle -24.5pts"       
## [403] "Geelong +7.5pts"           "Adelaide +27.5pts"        
## [405] "Richmond -27.5pts"         "Brisbane -18.5pts"        
## [407] "Carlton +18.5pts"          "Essendon +9.5pts"         
## [409] "Adelaide -2.5pts"          "Geelong +2.5pts"          
## [411] "Carlton +22.5pts"          "St Kilda -22.5pts"        
## [413] "Hawthorn -27.5pts"         "Melbourne -42.5pts"       
## [415] "Western Bulldogs +42.5pts" "GWS +11.5pts"             
## [417] "Richmond -11.5pts"         "Collingwood -14.5pts"     
## [419] "Fremantle +29.5pts"        "Port Adelaide -29.5pts"   
## [421] "Richmond -34.5pts"         "St Kilda +34.5pts"        
## [423] "Adelaide -9.5pts"          "Brisbane +9.5pts"         
## [425] "Geelong -11.5pts"          "Melbourne +11.5pts"       
## [427] "Hawthorn -38.5pts"         "GWS +8.5pts"              
## [429] "Port Adelaide -8.5pts"     "Essendon -3.5pts"         
## [431] "Sydney +3.5pts"            "Brisbane +31.5pts"        
## [433] "Geelong -31.5pts"          "GWS -39.5pts"             
## [435] "Carlton +20.5pts"          "Gold Coast -20.5pts"      
## [437] "North Melbourne -8.5pts"   "West Coast +8.5pts"       
## [439] "Western Bulldogs +22.5pts" "Geelong +18.5pts"         
## [441] "Richmond -18.5pts"         "St Kilda -7.5pts"         
## [443] "Brisbane -4.5pts"          "North Melbourne +4.5pts"
unique(df3$Team)
##  [1] "Carlton"                "Collingwood"           
##  [3] "Adelaide"               "St Kilda"              
##  [5] "Sydney"                 "Gold Coast"            
##  [7] "Essendon"               "North Melbourne"       
##  [9] "Fremantle"              "Richmond"              
## [11] "Western Bulldogs"       "Hawthorn"              
## [13] "Greater Western Sydney" "West Coast"            
## [15] "Brisbane Lions"         "Geelong"               
## [17] "Melbourne"              "Port Adelaide"

From here we can see that not all the team names are aligned so we need to fix them up, as an example we have the Adelaide Crows in 2017 and Adelaide in 2018. When we try and join to Squiggle we will miss out some games in 2017 because its trying to match Adelaide (from squiggle) with Adelaide Crows from betfair.

To confirm this we can use below

df_bookie%>%filter(Team %in% c("Adelaide Crows", "Adelaide"))
## # A tibble: 29 x 3
##    Date       Team           WAP               
##                                
##  1 2017-04-01 Adelaide Crows 1.8413133095902039
##  2 2017-04-15 Adelaide Crows 1.1876003204498842
##  3 2017-04-22 Adelaide Crows 1.2818905566923648
##  4 2017-05-06 Adelaide Crows 1.1829114641026119
##  5 2017-05-27 Adelaide Crows 1.19012452955724  
##  6 2017-06-02 Adelaide Crows 1.817133213487137 
##  7 2017-06-09 Adelaide Crows 1.1764993689503755
##  8 2017-06-22 Adelaide Crows 1.116772609240404 
##  9 2017-07-30 Adelaide Crows 1.5478971535189769
## 10 2017-08-18 Adelaide Crows 1.6920023163626901
## # … with 19 more rows
inner_join(df_bookie,df3, by=c("Team","Date"))%>%
  filter(Team %in% c("Adelaide Crows", "Adelaide"))
## # A tibble: 195 x 12
##    Date       Team  WAP   source correct hconfidence margin   err tip  
##                          
##  1 2018-04-07 Adel… 1.36… Squig…       1        31     24    25   Adel…
##  2 2018-04-07 Adel… 1.36… Aggre…       1        33.7   16.7  32.3 Adel…
##  3 2018-04-07 Adel… 1.36… The A…       1        34.8   14    35   Adel…
##  4 2018-04-07 Adel… 1.36… Punte…       1        27.1   NA    NA   Adel…
##  5 2018-04-07 Adel… 1.36… Graft        1        29.1   21    28   Adel…
##  6 2018-04-07 Adel… 1.36… PlusS…       1        42.2   12    37   Adel…
##  7 2018-04-07 Adel… 1.36… Matte…       1        31.1   18.9  30.1 Adel…
##  8 2018-04-07 Adel… 1.36… Footy…       1        33     22    27   Adel…
##  9 2018-04-07 Adel… 1.36… Live …       1        38.2   11    38   Adel…
## 10 2018-04-07 Adel… 1.36… Statt…       1        40.3   11    38   Adel…
## # … with 185 more rows, and 3 more variables: round , year ,
## #   H_A 

So lets just fix up the team names

df_bookie<-df_bookie %>%
     mutate(Team=replace(Team,Team=="Adelaide Crows", "Adelaide")) %>%
   mutate(Team=replace(Team,Team=="Sydney Swans", "Sydney")) %>%
   mutate(Team=replace(Team,Team=="Gold Coast Suns", "Gold Coast")) %>%
   mutate(Team=replace(Team,Team=="GWS Giants", "Greater Western Sydney")) %>%
   mutate(Team=replace(Team,Team=="GWS", "Greater Western Sydney")) %>%
   mutate(Team=replace(Team,Team=="West Coast Eagles", "West Coast")) %>%
   mutate(Team=replace(Team,Team=="Brisbane", "Brisbane Lions")) %>%
   mutate(Team=replace(Team,Team=="Geelong Cats", "Geelong")) %>%
   mutate(Team=replace(Team,Team=="Melbourne Demons", "Melbourne")) %>%
       as.data.frame()


df_joined<-left_join(df3,df_bookie, by=c("Team","Date"))

Step 5 Check the Join

So remember what we wanted originally, we wanted to join betting data to the squiggle data. Our squiggle data was a dataframe called df3 and our bookie data was a dataframe called df_bookie. One way to check our join, is to make sure the dimension lines up.

We do this using dim.

dim(df3)
## [1] 10734    11
dim(df_bookie)
## [1] 956   3
dim(df_joined)
## [1] 10734    12

Our dimension for df3 is 7842 rows and 11 columns, and our joined data df_joined is 7842 rows and 12 columns, i.e. it is the same as df3 (squiggle data) but has an extra column (betfair odds)

So it seems as though we have a clean dataset to analyse. Now we just got to go ahead and do it!

A quick analysis

Someone asked me who do you think tips underdogs the best?

Well if you just wanted to know who has most winning underdog ‘bets’ (I don’t know if any of the squigglers bet).

df_joined%>%filter(WAP>2 &correct ==1 & Team==tip)%>%
  group_by(source)%>%
  summarise(count=n())%>%
  arrange(desc(count))
## # A tibble: 14 x 2
##    source                count
##                     
##  1 HPN                      12
##  2 Footy Maths Institute    11
##  3 Graft                    10
##  4 Stattraction             10
##  5 Massey Ratings            9
##  6 Figuring Footy            7
##  7 Matter of Stats           7
##  8 PlusSixOne                7
##  9 Squiggle                  7
## 10 The Arc                   7
## 11 Aggregate                 6
## 12 Live Ladders              5
## 13 Swinburne                 3
## 14 Punters                   1

That tells me Footy Maths institute had the most winning underdog bets, but just how many times did they have to bet?

df_joined%>%filter(WAP>2 & Team==tip)%>%
    group_by(source, correct)%>%
    summarise(count=n())%>%
    group_by(source)%>%
    mutate(total_bets=sum(count), pert=count/total_bets)%>%
    filter(correct==1)%>%
    arrange(desc(pert))
## # A tibble: 14 x 5
## # Groups:   source [14]
##    source                correct count total_bets  pert
##                               
##  1 Punters                     1     1          1 1    
##  2 Figuring Footy              1     7         11 0.636
##  3 Massey Ratings              1     9         16 0.562
##  4 Aggregate                   1     6         12 0.5  
##  5 Footy Maths Institute       1    11         22 0.5  
##  6 HPN                         1    12         24 0.5  
##  7 Squiggle                    1     7         15 0.467
##  8 Graft                       1    10         22 0.455
##  9 Live Ladders                1     5         11 0.455
## 10 Stattraction                1    10         26 0.385
## 11 Matter of Stats             1     7         19 0.368
## 12 PlusSixOne                  1     7         19 0.368
## 13 The Arc                     1     7         19 0.368
## 14 Swinburne                   1     3         14 0.214

Note we can automatically download the AFL file using the following script.

library(readxl)
filetodownload <- "http://www.aussportsbetting.com/historical_data/afl.xlsx"
download.file(filetodownload,"aflodds.xlsx",mode="wb")


res <-read_excel("aflodds.xlsx", sheet = 1,skip = 1) 

To leave a comment for the author, please follow the link and comment on their blog: Analysis of AFL.

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