Baseball Hacks

Chart Team Stats in Real Time

Use Perl to dynamically fetch data from the Web, and then use R to create scatter plots.

ESPN’s stats page has lots of good data about team performance. As you can see in Figure 4-18, the data is comprehensive and useful, but it appears in long, boring tables. This hack shows how to use Perl to extract this data, directly from the Web and from R, to create nice charts and graphs.

Figure 4-18. ESPN’s team stats page

You access the data using a URL that looks like this: http://sports.espn.go.com/mlb/teams/batting?team=TeamID. TeamID is a three-letter abbreviation. For example, if you’re looking for data on the Red Sox, replace TeamID with BOS; if you’re looking for data on the Tigers, replace TeamID with DET; and so on. (If you’re in doubt about a team’s ID, go to the ESPN web site, select the stats for the team you want, and then read the URL.)

The Code

This hack is comprised of two parts: one part extracts the data from the ESPN site, and the other creates the display. This first script queries http://www.espn.com for the TeamID value you pass it and then writes a pipe (|) delimited text file that you can easily import into R. Save the following listing into a file called get_data.pl:

 #!/usr/bin/perl # PERL MODULES TO USE use LWP::Simple; use HTML::TableExtract; # WHAT TEAM TO PULL? $TeamID = $ARGV[0]; # CREATE FILE TO PLACE OUTPUT INTO $outfile = 'data.txt'; ...