IT 117: Intermediate Scripting

IT 117: Intermediate Scripting
Homework 2

Due
What You Need to Do
Setup On Your Machine
Specification
Functions
Test Code
Output
Suggestions
Testing on Your Machine
Copy the Script to Unix
Testing the Script on Unix (Optional)

Due

Sunday, February 9th at 11:59 PM

What You Need to Do

Create the script hw2.py
Make sure it obeys the rules in Rules for Homework Scripts
Make sure the script has a hashbang line and is executable
Move it to an an hw2 directory on pe15.cs.umb.edu

Setup On Your Machine

Open a text editor.
I would suggest the text editor built into the program IDLE.
Save the file as hw2.py
Copy the file red_sox.txt from /home/ghoffman/course_files/it117_files.
Use FileZilla to do this.

Specification

The script will read in a file with data about Red Sox games

The file looks like this

2011-07-02      Red Sox @  Astros       Win 7-5
2011-07-03      Red Sox @  Astros       Win 2-1
2011-07-04      Red Sox vs Blue Jays    Loss 7-9

It will calculate and print the average number of games the Red Sox won
The script must contain a two functions
- open_file_read
- team_average

Functions

open_file_read

Header
```
def open_file_read(filename):
```
The function will try to create a file object using the parameter filename
This should be done inside a try/except statement
If the object is created it should be returned
If a file object cannot be created the function should print an error message and quit

team_average

Header
```
def team_average(file):
```
The function will loop through the file totaling the number of games the Red Sox won
And the number of lines
It will use these values to calculate the percentage of the games the games the Red Sox won
It should return this percentage as an integer

Here is the algorithm for the part that creates the percentage

	
set line_count to 0
set win_count to 
for each line in the file:
   add 1 to line_count
   if line contains "Win":
      add 1 to win_count
set average to win_count / line_count
return the rounded average times 100

Test Code

Your script must contain the following statements

They should appear at the bottom of your script

open_file_read("xxxxxxx")
file = open_file_read("red_sox.txt")
average = team_average(file)
print(average)

This code will only work if you have copied red_sox.txt into the same directory as your script
You will find this file in /home/ghoffman/course_files/it117_files

Output

The output should look something like this
```
Cannot open xxxxxxx
76
```

Suggestions

Write this script in stages
Test your script at each step
Print the steps below
And check them off as you finish each one

Create the script hw2.py using the editor built into IDLE.
Enter the header for open_file_read and team_average into the script.
Under each header write the Python statement pass.
Copy the test code above into the script.
Enter # before the last two lines in the test code.
Make the script executable.
Run the script.
You should see nothing.
Remove the pass statement from open_file_read.
In its place write a try/except statement.
The try block should contain code to create a file object for reading using the using the filename parameter.
Under this statement return the file object.
In the except clause print an error message.
Run the script.
You should see
```
Cannot open xxxxxxx
```
Remove the pass statement from team_average.
Create the variable line_count and set it to 0.
Create the variable win_count and set it to 0.
Now write a for loop that prints each line in the file.
Remove the # from the 2nd to last line of the test script.
Run the script.
Fix any errors you find.
Remove the print statement.
Replace it with a statement that adds 1 to line_count.
Write an if statement that checks that the line contains "Win".
If it does, add 1 to win_count.
Outside the for loop print win_count.
Run the script.
You should see
```
Cannot open xxxxxxx
19
```
Fix any errors you find.
Remove the print statement.
Replace it with a line that sets average to win_count divided by line_count.
Print line_count.
Run the script.
You should see
```
Cannot open xxxxxxx
0.76
```
Fix any errors you find.
Delete the print statement.
Replace it with a statement that returns 100 times the rounded value of average.
Remove the # from the last line of the test code. Run the script.
Fix any errors you find.

Testing on Your Machine

Open IDLE
Use the Open command in IDLE to open hw2.py
Under the Run menu, select Run Module
Your output should look something like this
```
Cannot open xxxxxxx
76
```

Copy the Script to Unix

Open FileZilla and connect to pe15.cs.umb.edu
Go to your it117 directory
Go to your hw directory
Right-click in the whitespace inside the hw directory
Enter hw2 in the dialog box
Click and drag your script from the bottom left panel to the bottom right panel
Right-click on the file and select "Permissions" from the menu
Enter 755 in the box provided
This will make the script executable
Click and drag red_sox.txt from the bottom left panel to the bottom right panel

Testing the Script on Unix (Optional)

Connect to pe15.cs.umb.edu using an ssh client like putty.exe (Windows) or ssh (Mac)
Go to the directory for this exercise
```
cd  it117/hw/hw2
```
Run this script
```
python3 hw2.py
```
You should see something like this
```
Cannot open xxxxxxx
76
```