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, October 6th 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 reads in two similar files ...
and creates sets for each
It then uses set methods to show how the files differ
The script must contain 5 functions
- open_file_read
- count_words
- word_set_create
- different_words
- common_words

Functions

open_file_read

Header
```
def open_file_read(filename):
```
This function must try create a file object for reading ...
on the file whose name is given by the parameter filename
It should return the file object if succesful
If unsuccesful, it should print an error message ...
and return None

count_words

Header
```
def count_words(file):
```
This function must read in a file and count the words in that file
It must return the word count

The function should use the following algorithm

initialize word_count to 0
for line in file:
   create the list words by calling split on line
   add the length of the list words to word_count
return word_count

word_set_create

Header
```
def word_set_create(file):
```
This function must read a file and create a set of words in that file
All words added to the set must be lowercase
It must return the set

create the emtpy set word_set
for line in file:
   create the list words by running split on line
   for word in words:
      make word lowercase
      add word to word_set
return word_set

different_words

Header
```
def different_words(set_1, set_2)
```
This function must return the set of words that are in each set, but not the other
There is a set method that will return this set

common_words

Header
```
def common_words(set_1, set_2):
```
This function must return a set of words found in both sets
There is a set method that will return this set

Test Code

Your script must contain the following statements

filename_1 = "gettysburg.txt"
filename_2 = "gettysburg_hay.txt"
file_1     = open_file_read(filename_1)
file_2     = open_file_read(filename_2)
count_1 = count_words(file_1)
print(count_1)
count_2 = count_words(file_2)
print(count_2)
print()
file_1     = open_file_read(filename_1)
file_2     = open_file_read(filename_2)
word_set_1 = word_set_create(file_1)
word_set_2 = word_set_create(file_2)
print("Filename            Words  Unique Words")
print("---------------------------------------")
print(filename_1 + "      " + str(count_1) + "    " + str(len(word_set_1)))
print(filename_2 + "  " + str(count_2) + "    " + str(len(word_set_2)))
print()
different_word_set = different_words(word_set_1, word_set_2)
print("The two files have", len(different_word_set), "words in one file, but not the other" )
for word in sorted(different_word_set):
     print(word)
print()
common_words_set = common_words(word_set_1, word_set_2)
print("The two files have", len(common_words_set), "words in common")

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

272
268

Filename            Words  Unique Words
---------------------------------------
gettysburg.txt      272    132
gettysburg_hay.txt  268    135

The two files have  9 words in one file, but not the other
advanced
battle
battlefield
carried
field
fought
god
under
upon

The two files have 132 words in common

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.
Copy the test code to the bottom of the script.
Write a # as the first character in each line, except the first 4 lines.
By doing this you have "commented out" all but the first 4 lines of the test code.
This means only the first 4 lines of the test code will run.
Run the script.
Fix any errors you find.
Replace the pass statement in count_words with a statement assigns 0 to the variable count.
Now write a for loop that loops over the lines in the file.
Inside the loop print each line.
Uncomment the 5 lines in the test code starting with
```
count_1 = count_words(file_1)
```
Run the script.
You should not see any output.
Fix any errors you find.
Remove the print statement.
Create the list word_list by running split on each line.
Print word_list.
Run the script.
Fix any errors you find.
Remove the printstatement.
Replace it with a statement that increments count by the length of the list word_list.
Outside the for loop return count.
Run the script.
You should see
```
272
268
```
Fix any errors you find.
Remove the pass statement from word_set_create.
Replace it with a statement that creates the empty set word_set.
Now write a for loop that loops over the lines in the file.
Inside the loop print each line.
Uncomment the 4 lines in the test code beginning with
```
file_1     = open_file_read(filename_1)
```
Run the script.
Fix any errors you find.
Remove the print statement.
Create the list word_list by running split on each line.
Print word_list.
Run the script.
Fix any errors you find.
Remove the print statement.
In its place write another for loop that loops over the words in word_list.
word would be a good name for the loop variable.
Inside this second loop, print each word in word_list.
Run the script.
Fix any errors you find.
Remove the print statement.
Replace it with a statement that adds the lowercase value of each word to word_set.
Outside both loops, return word_set.
Uncomment the 5 lines in the test code beginning with
```
print("Filename            Words  Unique Words")
```
Run the script.
You should see
```
Filename            Words  Unique Words
---------------------------------------
gettysburg.txt      272    132
gettysburg_hay.txt  268    135
```
Fix any errors you find.
Remove the pass statement from different_words.
There is a set method which finds all the elements that are in set_1 but not set_2 as well as all elements that are in set_2 but not set_1.
Write a return statement which calls this method on the parameters set_1 and set_2.
Uncomment the 5 lines in the test code beginning with
```
different_word_set = different_words(word_set_1, word_set_2)
```
Run the script.
You should see
```
The two files have 9 words in one file, but not the other
advanced
battle
battlefield
carried
field
fought
god
under
upon
```
Fix any errors you find.
Remove the pass statement from common_words.
There is a set method what will return all the elements found in both sets.
Write a return statement which calls this method on the parameters set_1 and set_2.
Uncomment the last two lines in the test code.
Run the script.
You should see
```
The two files have  132  words in common
```
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

272
268

Filename            Words  Unique Words
---------------------------------------
gettysburg.txt      272    132
gettysburg_hay.txt  268    135

The two files have  9 words in one file, but not the other
advanced
battle
battlefield
carried
field
fought
god
under
upon

The two files have 132 words in common

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_hay.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