Module 4

In Module 4, you will learn the fundamentals of Python, a popular scripting language, and Regular Expressions, which give you power in text processing.

This article contains your assignments for Module 4.

Reading

The following articles on the online class wiki textbook contain information that will help you complete the assignments.

• Python
• Regular Expressions

Individual Assignments

Learn Python and Regular Expressions

Up to this point in CSE 330, you have used only one programming language: PHP. In Module 4, you will learn a new language: Python. Before starting this assignment, you should look over the online textbook article about Python. Additionally, you may find it helpful to look over the online textbook article about Regular Expressions.

Write some Regular Expressions

Please write regular expressions that do each the following:

1. Match an input string that contains at least one occurrence of the string "hello world"
2. Find all words in an input string that contain a triple vowel
3. Match an input string that is entirely a flight code, of the format AA####, where AA is a two-letter uppercase airline code, and #### is a three- or four-digit flight number

Save your regexes to a text file. The TA will test them in regexpal on Demo Day.

Baseball Stats Counter

The St. Louis Cardinals are the most legendary baseball team in the national league. In this exercise, you will be creating a Python script that reads box scores from a file and computes the Cardinals' players' batting averages in a particular season.

Tips and Instructions

• You should write a Python script file to solve this problem.
• You should use a regular expression to parse players' names, at-bats, hits, and runs from the input file.
• You may want to create a class to hold and compute information about each player.
• Your file should take one command-line argument: the path to an input file. If no path is given, your program should print a usage message.

Input

Sample input files may be found here: http://classes.engineering.wustl.edu/cse330/content/cardinals/

The top of the file contains a citation, and what follows is an entire season of Cardinals Baseball box scores. Each game starts with a title; for example:

=== St.Louis Cardinals vs. Chicago Cubs, 1940-04-19 ===

What follows are the performance of each player in that game. The format of each line is as follows:

XXX batted # times with # hits and # runs

where XXX is the player's name (you may assume that the name is unique), and each # are integers representing the number of "at bats", the number of "hits", and the number of "runs", respectively.

Output

Your script needs to output all players' batting average across the season. A player's batting average is that player's total hits divided by that player's total at-bats throughout the entire season. For example, Johnny Hopp was at bat 149 times in 1940, and he had 41 hits, so his batting average was 0.275.

Each line in the output should have the format:

XXX: #.###

where XXX is the player's name, and #.### is the player's batting average, rounded (not truncated) to three decimal places.

The players should be sorted by batting average, with the highest batting average on top. If two players have the exact same batting average (before rounding occurs), the order between those two players is unimportant.

For example, the correct output for the 1940 season is:

Pepper Martin: 0.316
Walker Cooper: 0.316
Johnny Mize: 0.314
Ernie Koy: 0.310
Enos Slaughter: 0.306
Joe Medwick: 0.304
Terry Moore: 0.304
Joe Orengo: 0.286
Jimmy Brown: 0.280
Marty Marion: 0.279
Don Gutteridge: 0.276
Johnny Hopp: 0.275
Creepy Crespi: 0.273
Mickey Owen: 0.265
Bill DeLancey: 0.250
Don Padgett: 0.242
Stu Martin: 0.238
Eddie Lake: 0.222
Hal Epps: 0.214
Lon Warneke: 0.209
Harry Walker: 0.185
Max Lanier: 0.179
Bill McGee: 0.178
Carl Doyle: 0.174
Mort Cooper: 0.157
Clyde Shoun: 0.145
Carden Gillenwater: 0.130
Bob Bowman: 0.067

Grading

We will be grading the following aspects of your work. There are 50 points total.

1. Regular Expressions (15 Points):
   • Regular Expression 1 Correct (5 points)
   • Regular Expression 2 Correct (5 points)
   • Regular Expression 3 Correct (5 points)
2. Baseball Stats Counter (35 Points):
   • Solution is written entirely in Python, except with permission from the instructor (8 points)
   • Correct usage of a regular expression to parse each line of the input file (8 points)
   • Script prints a usage message if a command line argument is not present (4 points)
   • Output is correct for the 1940 test case (15 points)

     This includes sorting and rounding.