IT 117: Intermediate Scripting

IT 117: Introduction to 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, September 15th 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 qz_04_grades.txt from /home/ghoffman/course_files/it117_files.
Use FileZilla to do this.

Specification

The script must read a file with lines like this
```
95	Alan Ball
98	Eddie Bauer
80	Dan Franks
...
```
It must calculate the average score and print it
The score must be an integer
The script must contain 2 functions
- open_file_read
- average_score

Functions

open_file_read

Header
```
def open_file_read(filename):
```
The function must try to create a file object for reading ...
on the file whose name is given by the parameter filename
If it can create the file object it should return it
It it cannot it should print an error message and return None

average_score

Header
```
def average_score(file):
```
The function must use the file object given to it by the parameter file ...
to loop through the file and calcuate the average score
It should return the score rounded to an intger

Test Code

Your script must contain the following statements

filename = input("File name: ")
file = open_file_read(filename)
if file:
    average = average_score(file)
    print()
    print("Average", average

They should appear at the bottom of your script
This code will only work if you have copied qz_04_grades.tx 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
```
File name: qz_04_grades.txt

Average 84
```
Where the entry in blue is supplied by the user

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 file hw2.py.
Enter the headers for open_file_read and average_score.
Under each header write the Python statement pass.
Run the script.
Fix any errors you find.
Replace the pass statement in open_file_read with code that creates a file object for reading.
Remember, you will get a runtime error if the file does not exist.
If the file object is created, the code should return it.
If not, the code should print an error message and return None.
Copy the first two lines of the test code into the bottom of the file.
Run the script entering both a real filename and the name of a file that does not exists.
Fix any errors you find.
Remove the pass statement from average_score.
Initialize the variables total and count to 0.
After this write a for loop that prints each line in the file.
Copy the next three lines of the test code to the bottom of the file.
Run the script entering qz_04_grades.txt when prompted.
Fix any errors you find.
Replace the print statement in average_score with an assignment statement that uses split to give values to the variables score, first and last.
For an example of what I mean, see Class Exercise 3.
Print the two new variables.
Run the script.
Fix any error you find.
Remove the print statement.
In its place write a statement that increased the value of count by 1.
After the for loop, return the value of count.
Add the last line from the test code. Run the script.
Fix any error you find.
Inside the for loop write and assignment statement that converts score into an integer.
Write a statement that adds score to total.
Change the return statement to return total.
Run the script.
Fix any error you find.
The average is calculated by dividing total by count.
You will have to round the result to get an integer.
Change the return statement so it returns the average.
Run the script.
Fix any error 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
The output should look something like this
```
File name: qz_04_grades.txt

Average 84
```
Where the entry in blue is supplied by the user

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 qz_04_grades.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
```
hw2.py
```
The output should look something like this
```
File name: qz_04_grades.txt

Average 84
```
Where the entry in blue is supplied by the user