Revision as of 19:50, 5 October 2015

--D. Thiebaut (talk) 12:17, 22 February 2015 (EST)

Preparation

Copy paste the program below in a new Idle window, and call it lab5Companion.py.
Save your new program to your working directory, where you normally save your lab programs.
Run the program. It should create 3 text files in your folder. You will be using them in this lab. The files are called:
- chocoQuotes.txt
- hargitay.txt
- joanneHarris.txt

[19:14:51] ~/Desktop/temp$: cat lab5prep.py
# lab5Companion.py
# D. Thiebaut
# This program will create several files in the directory
# where you will run it.
# The files are retrieved from a Web server, stored temporarily
# in a string, and stored in a local file on your disk.
# The 3 files are very, very short.
# Their names are:
# - chocoQuotes.txt
# - hargitay.txt
# - joanneHarris.txt

import urllib.request  # the lib that handles the url stuff

# main program
def main():

    # list of files to retrieve 
    URLs = [ "http://cs.smith.edu/~dthiebaut/111/files/chocoQuotes.txt", 
             "http://cs.smith.edu/~dthiebaut/111/files/hargitay.txt", 
             "http://cs.smith.edu/~dthiebaut/111/files/joanneHarris.txt" ]

    # get each file, one at a time
    for url in URLs:
        # fetch the file and put its contents in the
        # string text.
        response = urllib.request.urlopen( url )
        text     = response.read().decode( 'UTF-8' )
        
        # write text to file, in the same directory as this program.
        fileName  = url.split( "/" )[-1]
        file      = open( fileName, "w" )
        file.write( text + "\n" )
        file.close()

        # give feedback to user.
        print( "File {0:1} created in your folder".format( fileName ) )


main()

This lab deals with functions, passing parameters, and returning values. It is also about for you to start the Python.org documentation on the Web. The online documentation is a great help when writing programs. The Moodle submissions are due on Friday 10/08 at 11:55 p.m.

Searching the Python.org Doc

Open your Web browser and go to http://python.org
Click on Documentation, then on Python 3.x Docs.
In the Search Bar on the left, enter string methods.
Locate the result that contains Built-In Types, and go to that page. Locate the string methods there... (Hints: 4.7.1)
Look at all the different methods that strings offer you.
You're ready for the lab!

Functions

Working with Functions in the Console

This sections serves as a review for the end="..." optional parameter in print statements.
Try the following statements in the Python console:

>>> def test():
	print( "hello" )
	print( "there" )

	
>>> test()


>>> def test():
	print( "hello", end="" )
	print( "there" )

	
>>> test()

>>> def test():
	print( "hello", end="-" )
	print( "there" )

	
>>> test()
>>>

Notice what happens when you add the end="" construct in the print statement. It changes the way the print() function ends printing what it has to print. By default, if you do not have an end="" construct, print() brings the cursor to the next line. But this behavior can be changed. We are going to use this, in the new program below.

Teller Machine with Functions

Without looking at your notes, (but if you get stuck, it's ok to look up your notes or the class notes on the Web), try to recreate the teller machine program that prompts the user for some integer amount of dollars, and returns the number of bills.
Recommendations:

create a function to get the amount from the user: the function asks the user to enter some amount, gets the amount with inpu(), then returns it to the main() program.
create a function that receives the amount to be broken, and prints the breakdown in various amounts of bills.
If you are ambitious, try to think of a way to write a function that receives an amount (say 17), and some denomination (say 10), and prints "1 $10-bill(s)", and returns 7. One you have this function written, you can call it 4 times to break down the amount into $20-, $10-, $5- and $1-bills.

Functions and Stick Figure, Version 1

This section will be cleaner if you start a new program, rather than add to an existing program.
Add this code section to your new program:

def head():
    print( "  o" )

def leftArm():
    print( " /", end="" )

def torso():
    print( "O", end="" )

def rightArm():
    print( "\\" )

def leftLeg():
    print( " /", end="" )

def rightLeg():
    print( " \\" )

def stickFigure():
    head()
    leftArm()
    torso()
    rightArm()
    leftLeg()
    rightLeg()

def main():
    stickFigure()

main()

Take a close look at the program. Locate the end="" construct, which prevents the print from going to the next line when it's done.
Notice also the "\\" string. Because the '\' character is used to print special characters, like '\n' (new line), or '\t' (tab), if we want to print a regular backslash character, we have to use 2 backslashes next to each other.

Run the program. Notice how it displays a stick figure.

Functions and Stick Figure, Version 2

Modify the stick figure program so that it looks like the code below:

def head():
    print( "  o" )

def leftArm():
    print( " /", end="" )

def torso():
    print( "O", end="" )

def rightArm():
    print( "\\" )

def leftLeg():
    print( " /", end="" )

def rightLeg():
    print( " \\" )

def body():
    leftArm()
    torso()
    rightArm()

def newStickFigure():
    head()
    body()
    leftLeg()
    rightLeg()

def main():
    newStickFigure()

main()

Observe how the code is different, and the new function body() is used to display the body of the stick figure (torso plus arms).
Using the example of body(), add a new function called legs() that will call leftLeg() and rightLeg() to draw both legs. Modify newStickFigure() by removing the calls to leftLeg() and rightLeg(), and adding instead a call to legs(). Your new function should look something like this:

def newStickFigure():
    head()
    body()
    legs()

Trim DNA

Assume that we have a string containing the description of a DNA sequence, say "AAGACTAAAAAAGACTT." (DNA sequences are made of 4 symbols: A, C, G, and T.) Assume we know that "AGA" is a special marker in our DNA strings. So our string is marked in this way: "AAGACTAAAAAAGACTT."

Write a function called trimDNA( ) that receives the original DNA string as a parameter, and returns the string where everything on the left and right of the markers has been removed.

Example:

def main():
     DNA = "AAGACTAAAAAAGACTT"
     newDNA = trimDNA( DNA )
     print( newDNA )

The output would be

 AGACTAAAAAAGA

Happy Birthday!

Start with these three new functions:

def happyBirthday():
    print( "Happy birthday to you!" )

def happyBirthdayDear( name ):
    print( ("Happy birthday, dear " + name +"!" ) )

Write a third function called singSong() that calls the two functions above. When calling happyBirthdayDear( ... ), pass it some name, say yours, or "Dave", or one of your friends. You should get this kind of output:

Happy birthday to you!
Happy birthday, dear Dave!

Modify singSong() so that it displays a more appropriate version on the song:

Happy birthday to you!
Happy birthday to you!
Happy birthday, dear Dave!
Happy birthday to you!

Passing the Name as a Parameter

Modify your singSong( ) function one more time. I'm highlighting the lines that should change in your function:

def singSong( name ):
     ...
     ...
     happyBirthdayDear( name )
     ...

Now, make your program sing "Happy Birthday" to Dave, Karl, Jorge, and Tim!

Challenge #8

Make your program prompt the user for a name in the main() function.
Then main() will pass the name to singSong(), and your program will sing Happy Birthday to the person of your choice.

Challenge #9

Modify your solution program for Challenge 8 so that the user can enter several names on one line when prompted by your program. Your program then "sings" happy birthday to all the friends, one after the other...

Example:

Please enter the names of your friends: Jorge Karl Dave

Happy birthday to you!
Happy birthday to you!
Happy birthday, dear Jorge!
Happy birthday to you!

Happy birthday to you!
Happy birthday to you!
Happy birthday, dear Karl!
Happy birthday to you!

Happy birthday to you!
Happy birthday to you!
Happy birthday, dear Dave!
Happy birthday to you!

Moodle Submission

Submit your solution program for Challenge 9 to Moodle, in Section LAB 5 PB 9. You will need to rename your program lab5_9.py.

Reading Text From File

Open Finder or Windows Explorer and go to the folder that contains your lab5.py program, as well as your lab5Companion.py programs. Make sure the folder contains the 3 text files you created earlier.
Open the file name hargitay.txt. Verify that it contains the same poem we have been playing with.
Either create a new program or add a new main() function to your existing program (rename the original main, main2(), maybe?), and put the code below in the new function:

def main():
    fileName = "hargitay.txt"
    file = open( fileName, "r" )
    lines = file.readlines()
    file.close()

    for line in lines:
        print( line )

Run the program. Observe its output.
The reason for the double-spacing is that each line read from the file contains a '\n' at the end of it. And when you print such a line, the print() function adds its own \n at the end. This is why you get a blank line in between lines.
One way to remove the '\n' at the end of each line is to print the line as follows: print( line.rstrip() ). The rstrip() method right-strips the string of all white-space characters, which include spaces, tabs, and '\n'-characters.

Challenge #5

Make your program get the name of the file from the user, with an input() statement.
Then, make your program output the contents of the file in a box, as you did in Challenge 4.
Test your program by providing it with different file names:
- hargitay.txt
- joanneHarris.txt
- chocoQuotes.txt
Adjust the width of the box if necessary.

Challenge #6

Exact same challenge as Challenge 5, but this time start with this program, where I have replaced the .readlines() method with .read().

def main():
    fileName = input( "File name? " )
    file = open( fileName, "r" )
    text = file.read()
    file.close()

    print( "The type of text is", type( text ) )
    print( "text = ", text )

Note: when Python says that something is of type <class 'str'>, it means that it is a string.

Writing Text to File

Try this new version of main:

def main():
    fileName = "hargitay.txt"
    file = open( fileName, "r" )
    text = file.read()
    file.close()
    
    text = text.replace( "chocolate", "carrot" )
    text = text.replace( "Chocolate", "Carrot" )

    file = open( fileName, "w" )
    file.write( text + "\n" )
    file.close()

Open Finder or Windows Explorer, and take a look at the file "hargitay.txt", either with TextEdit or with Notepad. See anything different?
BTW, You can recreate the original file by running the lab5Companion.py program again.

Challenge #7

Modify the program so that it prompts the user for
- The name of the file to read from and write to, and
- a word

and make the program read the file, replace the word chocolate in it with the word the user picked, and save the resulting text back to the file.

Verify that your program works correctly, and that it modifies the file you select and replaces chocolate with the word you choose.

Moodle Submission

Rename your program lab5_7.py, and submit your solution program for Challenge #7 to Moodle, in the Lab 5 PB 7 section.

Splitting Long Strings (Optional: Skip it if you do not have time)

In this section you will see how to take text represented as a multi-line string, and process it various ways.

Long strings that span several lines can be created by enclosing them in triple quotes; either triple single-quotes (), or triple double-quotes (""").
Copy/paste the program below in a new program. You may call it lab5.py

# lab5.py

text = """Chocolate
Chocolate is the first luxury.
It has so many things wrapped up in it:
Deliciousness in the moment,
childhood memories,
and that grin-inducing
feeling of getting a reward for being good.
--Mariska Hargitay"""

def main():
    # make sure main knows that this variable exists
    global text
    
    # split the long string into individual lines
    lines = text.split( "\n" )

    # print each line
    for line in lines:
        print( line )

main()

Run the program. Verify that it outputs the entirety of the text.
Just to make sure we understand what the variable lines contain, make your program print lines, with a simple print( lines ) statement.
Observe that it's just a regular Python list.

Challenge #1

Modify your program, and make it print the poem so that each line is centered in a field of 60 spaces. You must use the text variable, and print its line. Do not create a new version of the poem!
Expected output

                         Chocolate                          
               Chocolate is the first luxury.               
          It has so many things wrapped up in it:           
                Deliciousness in the moment,                 
                    childhood memories,                     
                   and that grin-inducing                   
        feeling of getting a reward for being good.         
                     --Mariska Hargitay

Challenge #2

Make your program print the first line of the poem, centered, but also in uppercase.
If you need to review the string methods, you may want to go to this page.
Print a blank line after the title.
Make it display the other lines centered, without changing their case.
Print a blank line before the last line.
Expected output

                         CHOCOLATE             
             
               Chocolate is the first luxury.               
          It has so many things wrapped up in it:           
                Deliciousness in the moment,                 
                    childhood memories,                     
                   and that grin-inducing                   
        feeling of getting a reward for being good.         

                     --Mariska Hargitay

Challenge #3

One more modification. Now make your program print the last line right-justified in a field of 60 spaces.
The first line is still in upper-case.
Make it display the other lines centered, without changing their case.
If you need to review the string methods, you may want to go to this page.
Expected output

                         CHOCOLATE         
                 
               Chocolate is the first luxury.               
          It has so many things wrapped up in it:           
                Deliciousness in the moment,                 
                    childhood memories,                     
                   and that grin-inducing                   
        feeling of getting a reward for being good. 
        
                                          --Mariska Hargitay

Challenge #4

Make your program print the poem in a box. The top and bottom lines have 50 dashes in them.
Expected output

+--------------------------------------------------+
|                    CHOCOLATE                     |
|                                                  |
|          Chocolate is the first luxury.          |
|     It has so many things wrapped up in it:      |
|           Deliciousness in the moment,           |
|               childhood memories,                |
|              and that grin-inducing              |
|   feeling of getting a reward for being good.    |
|                                                  |
|                                --Mariska Hargitay|
+--------------------------------------------------+

Solution Programs

# Solution program for Lab #5
# All solutions to the challenges are stored in functions named challengex(),
# where x is 1, 2, 3, etc.
#

text = """Chocolate
Chocolate is the first luxury.
It has so many things wrapped up in it:
Deliciousness in the moment,
childhood memories,
and that grin-inducing
feeling of getting a reward for being good.
--Mariska Hargitay"""

def makeTextFile():
    file = open("hargitay.txt","w" )
    file.write( text )
    file.close()


def bar():
    print()
    print( "-"*80 )

def program0():
    # split the long string into individual lines
    lines = text.split( "\n" )

    # print each line
    for line in lines:
        print( line )

def challenge1():
    # split the long string into individual lines
    lines = text.split( "\n" )

    # print each line
    for line in lines:
        print( line.center( 60 ) )

def challenge2():
    # split the long string into individual lines
    lines = text.split( "\n" )

    # print title
    print( lines[0].upper().center( 60 ) )
    
    # print each line
    for line in lines[1: ]:
        print( line.center( 60 ) )


def challenge3():
    # split the long string into individual lines
    lines = text.split( "\n" )

    # get first and last line
    title = lines[0]
    lastLine = lines[-1]

    # get first line and print it
    print( title.upper().center( 60 ) )
    print()
    
    # print poem, between title and last line
    for line in lines[1:-1]:
        print( line )

    # print last line right-justified
    print( lastLine.rjust( 60 ) )


def challenge4():
    # split the long string into individual lines
    lines = text.split( "\n" )

    bar = "+" + "-"*50 + "+"

    # get first line and print it
    print( bar )
    print( "|" + lines[0].upper().center( 50 ) + "|" )
    
    # print each line
    for line in lines[1:-1]:
        print( "|" + line.center(50) + "|" )
    print( "|" + lines[-1].rjust(50) + "|" )
    print( bar )


def challenge5():
    # open the file and read the lines in
    fileName = "hargitay.txt"
    file = open( fileName, "r" )
    lines = file.readlines()
    file.close()

    # create a bar for the top and bottom of box
    bar = "+" + "-"*50 + "+"

    # get first line and print it
    print( bar )
    print( "|" + lines[0].upper().center( 50 ) + "|" )
    
    # print each line
    for line in lines[1:-1]:
        print( "|" + line.center(50) + "|" )
    print( "|" + lines[-1].rjust(50) + "|" )
    print( bar )

def challenge6():
    # open the file and read the lines in
    fileName = "hargitay.txt"
    file = open( fileName, "r" )
    text = file.read()
    lines = text.split( "\n" )
    file.close()

    # create a bar for the top and bottom of box
    bar = "+" + "-"*50 + "+"

    # get first line and print it
    print( bar )
    print( "|" + lines[0].upper().center( 50 ) + "|" )
    
    # print each line
    for line in lines[1:-1]:
        print( "|" + line.center(50) + "|" )
    print( "|" + lines[-1].rjust(50) + "|" )
    print( bar )


def challenge7():
    # get the user input
    fileName = input( "File name? " )
    word     = input( "Word to swap in? " )
    
    # open the file and read the lines in
    file = open( fileName, "r" )
    text = file.read()
    file.close()

    # replace chocolate by word before we split the text
    text = text.replace( "Chocolate", word.capitalize() )
    text = text.replace( "chocolate", word.lower() )
    text = text.replace( "CHOCOLATE", word.upper() )

    file = open( fileName, "w" )
    file.write( text )
    file.close()

  


# --------------------- stickFigure -----------------------

def head():
    print( "  o" )

def leftArm():
    print( " /", end="" )

def torso():
    print( "O", end="" )

def rightArm():
    print( "\\" )

def leftLeg():
    print( " /", end="" )

def rightLeg():
    print( " \\" )

def stickFigure():
    head()
    leftArm()
    torso()
    rightArm()
    leftLeg()
    rightLeg()

def body():
    leftArm()
    torso()
    rightArm()

def legs():
    leftLeg()
    rightLeg()

def newStickFigure():
    head()
    body()
    legs()

# --------------------- stickFigure1 ----------------------

def leftForearm1():
    print( " /", end="" )

def sword1():
    print( "+=====>" )

def leftArm1():
    print( " \\", end="" )

def head1():
    print( "O", end="" )

def rightArm1():
    print( "___" )

def body1():
    print( "  |" )
    print( "  |" )

def leftThigh1():
    print( " / ", end="" )

def rightThigh1():
    print( "\\" )

def leftCalf1():
    print( "/   ", end ="" )

def rightCalf1():
    print( "\\" )

def stickFigure1():
    leftForearm1()
    sword1()
    leftArm1()
    head1()
    rightArm1()
    body1()
    leftThigh1()
    rightThigh1()
    leftCalf1()
    rightCalf1()


# ---------------------------------------------------------


def happyBirthday():
    print( "Happy birthday to you!" )

def happyBirthdayDear( name ):
    print( "Happy birthday, dear " + name +"!"  )

def singSong( name ):
    happyBirthday()
    happyBirthday()
    happyBirthdayDear( name )
    happyBirthday()


def challenge8( ):
    # get the name from the user
    name = input( "Who's birthday should we celebrate? " )

    # sing the song for that person
    singSong( name )

# challenge 9
def happyBirthday():
    print( "Happy birthday to you!" )

def happyBirthdayDear( name ):
    print( "Happy birthday, dear " + name +"!"  )

def singSong( name ):
    happyBirthday()
    happyBirthday()
    happyBirthdayDear( name )
    happyBirthday()

def challenge9( ):
    # get a line of names, separated by spaces
    line = input( "? " )

    # remove extra spaces at the front or back
    line = line.strip()

    # split the line into individual names, and sing song for each
    for name in line.split( " " ):
        singSong( name )
        # blank line separates the different songs
        print()


def bar():
    print( "\n" + ( "-"*30 ) + "oOo" + ("-"*30 ) +"\n" )

    
def main():
    
    challenge1()
    bar()
    challenge2()
    bar()
    challenge3()
    bar()
    challenge4()
    bar()
    challenge5()
    bar()
    challenge6()
    bar()
    challenge7()
    bar()
    challenge8()
    bar()
    challenge9()
    bar()
  
    
main()

</showafterdate>

...

@@ Line 62: / Line 62: @@
 <br />
 <bluebox>
-Although this has few Moodle submissions, make sure you work on '''all''' the challenges.  If you skip them, you are only making it harder for you to learn Python and making future challenges that much harder.   A little bit of effort regularly beats a huge effort later!   The Moodle submissions are due on Friday 10/08 at 11:55 p.m.
+This lab deals with functions, passing parameters, and returning values.  It is also about for you to start the Python.org documentation on the Web.   The online documentation is a great help when writing programs.  The Moodle submissions are due on Friday 10/08 at 11:55 p.m.
 </bluebox>
 <br />
 __TOC__
 <br />
+=Searching the Python.org Doc=
+<br />
+* Open your Web browser and go to http://python.org
+* Click on '''Documentation''', then on '''Python 3.x Docs'''.
+* In the '''Search Bar''' on the left, enter '''string methods'''.
+* Locate the result that contains '''Built-In Types''', and go to that page.   Locate the string methods there... (Hints: 4.7.1)
+* Look at all the different methods that strings offer you.
+* You're ready for the lab!
+<br />
 =Functions=
 <br />

Difference between revisions of "CSC111 Lab 5 2015b"

Revision as of 19:50, 5 October 2015

Preparation

Contents

Searching the Python.org Doc

Functions

Working with Functions in the Console

Teller Machine with Functions

Functions and Stick Figure, Version 1

Functions and Stick Figure, Version 2

Trim DNA

Happy Birthday!

Passing the Name as a Parameter

Challenge #8

Challenge #9

Moodle Submission

Reading Text From File

Challenge #5

Challenge #6

Writing Text to File

Challenge #7

Moodle Submission

Splitting Long Strings (Optional: Skip it if you do not have time)

Challenge #1

Challenge #2

Challenge #3

Challenge #4

Solution Programs

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