Historical NHL Skater Stats.R

###############################################################################
# Author: @BrockTibert
# Purpose: Collect Historical NHL Skater Stats 1960 - 2011 (in progress)
# Date: February 2011
#
# Used: R Version 2.12.1, Windows 7 Pro, StatET Plugin for Eclipse
#
# # Copyright (c) 2011, under the Simplified BSD License.  
# For more information on FreeBSD see: http://www.opensource.org/licenses/bsd-license.php
# All rights reserved. 
###############################################################################

#-----------------------------------------------------------------------
# set up script level basics
#-----------------------------------------------------------------------

## libraries
library(XML)

## directory for the project
DIR <- "C:/Users/Brock/Documents/My Dropbox/Projects/NHL"
setwd(DIR)



#-----------------------------------------------------------------------
# Create a function that will take a year and return a dataframe
#-----------------------------------------------------------------------

GrabSkaters <- function(S) {
    
    # The function takes parameter S which is a string and represents the Season
    # Returns: data frame    
    
    ## create the URL
    URL <- paste("http://www.hockey-reference.com/leagues/NHL_", 
            S, "_skaters.html", sep="")
    
    ## grab the page -- the table is parsed nicely
    tables <- readHTMLTable(URL)
    ds.skaters <- tables$stats
    
    ## determine if the HTML table was well formed (column names are the first record)
    ## can either read in directly or need to force column names
    ## and 
    
    ## I don't like dealing with factors if I don't have to
    ## and I prefer lower case
    for(i in 1:ncol(ds.skaters)) {
            ds.skaters[,i] <- as.character(ds.skaters[,i])
            names(ds.skaters) <- tolower(colnames(ds.skaters))
    }
    
    ## fix a couple of the column names
    colnames(ds.skaters)
    names(ds.skaters)[10] <- "plusmin"
    names(ds.skaters)[17] <- "spct"
    
    ## finally fix the columns - NAs forced by coercion warnings
    for(i in c(1, 3, 6:18)) {
            ds.skaters[,i] <- as.numeric(ds.skaters[, i])
    }
    
    ## convert toi to seconds, and seconds/game
    ds.skaters$seconds <- (ds.skaters$toi*60)/ds.skaters$gp
    
    ## remove the header and totals row
    ds.skaters <- ds.skaters[!is.na(ds.skaters$rk), ]
    ds.skaters <- ds.skaters[ds.skaters$tm != "TOT", ]
	
	## add the year
	ds.skaters$season <- S
    
    ## return the dataframe
    return(ds.skaters)
    
}




#-----------------------------------------------------------------------
# Use the function to loop over the seasons and piece together
#-----------------------------------------------------------------------

## define the seasons -- 2005 dataset doesnt exist
## if I was a good coder I would trap the error, but this works
SEASON <- as.character(c(1960:2004, 2006:2011))


## create an empy dataset that we will append to
dataset <- data.frame()

## loop over the seasons, use the function to grab the data
## and build the dataset
for (S in SEASON) {
	
	temp <- GrabSkaters(S)
	dataset <- rbind(dataset, temp)
	print(paste("Completed Season ", S, sep=""))
	
	## pause the script so we don't kill their servers
	Sys.sleep(3)
	
}

## save the dataset
write.table(dataset, "Historical Skater Stats.csv", sep=",",
		row.names=F)