IT 117: Intermediate Scripting

IT 117: Introduction to Scripting
Homework 5

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, March 1st at 11:59 PM

What You Need to Do

Create the script hw5.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 hw5 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 hw5.py
Copy the files gettysburg.txt and gettysburg_hay.txt from /home/ghoffman/course_files/it117_files.
Use FileZilla to do this.

Specification

This script will create sets from text files and perform various operations on them
The script must contain 5 functions
- open_file_read
- word_set_from_file
- ordered_word_set_print
- word_count
- set_difference

Functions

open_file_read

Header
```
def open_file_read(filename):
```
This script tries to create a file object for reading
The name of the file is given by the parameter filename
If the script can create the object it should return it
If it is cannot create the object it should print an error message and return None

word_set_from_file

Header
```
def word_set_from_file(filename):
```
This function must read in a file with many words on a line

The file will have lines like this

Four score and seven years ago our fathers brought forth on this
continent a new nation conceived in Liberty and dedicated to the
...

It should read in each line and create a set from the words in the file
All words should be made lowercase before being added to the set
The function must return this set
The function should use the following algorithm

	create an empty set
	for each line in the file:
	   create the list of words by running split() on line
	   for each word in the word list:
	      make the word lowercase and add it to the set
	return the set

ordered_word_set_print

Header
```
def ordered_word_set_print(set):
```
This function must print the elements of a set in alphabetical order

word_count

Header
```
def word_count(filename):
```
It must read in a file and count the words in the file
It must return this word count
The function should use the following algorithm

	create a file object for reading
	set count equal to 0
	for each line in the file:
		create list of the words in the file using split()
		add the length of the list to count
	return count

set_difference

Header
```
def set_difference(set_1, set_2):
```
This script must return the difference between set_1 and set_2

Test Code

Your script must contain the following statements

filename_1 = "gettysburg.txt"
set_1  = word_set_from_file(filename_1)
ordered_word_set_print(set_1)
print()
print("Words in " + filename_1 + ":" + str(word_count(filename_1)))
filename_2 = "gettysburg_hay.txt"
set_2  = word_set_from_file(filename_2)
print()
print("Words in " + filename_1 + " not in " + filename_2)
ordered_word_set_print(set_difference(set_1, set_2))
print()
print("Words in " + filename_2 + " not in " + filename_1)
ordered_word_set_print(set_difference(set_2, set_1))

They should appear at the bottom of your script
This code will only work if you have copied gettysburg.txt and gettysburg_hay.txt into the same directory as your script
You will find these files in /home/ghoffman/course_files/it117_files

Output

The output should look something like this

a
above
add
advanced
...
will
work
world
years

Words in gettysburg.txt:272

Words in gettysburg.txt not in gettysburg_hay.txt
advanced
battle
field
fought
god
under

Words in gettysburg_hay.txt not in gettysburg.txt
battlefield
carried
upon

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 hw5.py.
Enter the headers for each of the required functions.
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 the body of the code from your hw4.py script.
Run the script.
Fix any errors you find.
Replace the pass statement in word_set_from_file with a statement that creates the empty set words_set.
Write a statement that creates a file object by calling open_file_read using the filename parameter.
Copy the test code to the bottom of the file.
Comment out all but the first two lines of the test code.
Run the script.
You should not see any output.
Fix any errors you find.
After the statement that creates a file object, write a for loop with the loop variable line
Inside the for loop get rid of the linefeed at the end of the line by assign line to the result of running strip on line.
Print line.
Run the script.
You should see something like this
```
Four score and seven years ago our fathers brought forth on this
continent a new nation conceived in Liberty and dedicated to the
proposition that all men are created equal
...
```
Fix any errors you find.

Remove the print statement.
Create the list words by running the split() method on line.
Print this list.
Run the script.
You should see something like this

['Four', 'score', 'and', 'seven', 'years', 'ago', 'our', 'fathers', 'brought', 'forth', 'on', 'this']
['continent', 'a', 'new', 'nation', 'conceived', 'in', 'Liberty', 'and', 'dedicated', 'to', 'the']
...

Fix any errors you find.

Remove the print statement.
Write a for loop using the loop variable word.
Inside the loop print each word.
Run the script.
You should see something like this
```
Four
score
and
...
```
Fix any errors you find.
Remove the print statement.
Make each word lowercase using the string method lower.
You have to do this with an assignment statement because strings cannot be changed in Python.

Write a statement that adds the word to the set words_set.
Outside both for loops print words_set.
Run the script.
You should see something like this, although the order may be different
```
{'government', 'proposition', 'for', 'a', 'struggled' ...
```
Fix any errors you find.
Remove the print statement from word_set_from_file.
Write a statement that returns the set.
Remove the pass statement from ordered_word_set_print.
Write a statement that prints the argument set.
Uncomment the next line in the test code.
Run the script.
You should see something like this, although the order may be different
```
{'a', 'fathers', 'men', 'forth', 'we', 'created' ...
```
Fix any errors you find.
Remove the print statement from ordered_word_set_print.
Write a for loop that prints each word in the set.
Make sure it prints them in alphabetical order.
Run the script.
You should see
```
a
above
add
advanced
```
Fix any errors you find.
Remove the pass statement from word_count.
Write a statement that sets the variable count to 0.
Write a statement that creates a file object by calling open_file_read.
Uncomment the next two lines in the test code.
Run the script.
You should only see the words in the set you created above.
Fix any errors you find.
Write a for loop that prints each line in the file.
Run the script.
You should see the lines of the file at the bottom of your output but no new output.
Fix any errors you find.
Remove the print statement in the for loop.
Create a list of all the words in the line using split() on the line.
Add the length of this list to count.
Outside the for loop print count.
Run the script.
At the bottom of the output you should see
```
272
Words in gettysburg.txt:None
```
Fix any errors you find.
Remove the print statement.
Replace it with a statement that returns count. Run the script.
At the bottom of the output you should see
```
Words in gettysburg.txt:272
```
Fix any errors you find.
Remove the pass statement in set_difference.
Replace it with a statement the returns the difference between the two parameters, set_1 and set_2.
Uncomment the remaining lines in 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 hw5.py
Under the Run menu, select Run Module

Your output should look something like this

a
above
add
advanced
...
will
work
world
years

Words in gettysburg.txt:272

Words in gettysburg.txt not in gettysburg_hay.txt
advanced
battle
field
fought
god
under

Words in gettysburg_hay.txt not in gettysburg.txt
battlefield
carried
upon

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 hw5 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 gettysburg.txt and gettysburg.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/hw5
```
Run this script
```
hw5.py
```

You should see something like this

a
above
add
advanced
...
will
work
world
years

Words in gettysburg.txt:272

Words in gettysburg.txt not in gettysburg_hay.txt
advanced
battle
field
fought
god
under

Words in gettysburg_hay.txt not in gettysburg.txt
battlefield
carried
upon