RWET Programming Exercise B

exercise_b.py

#
# RWET Programming Exercise B
#
# This worksheet is also a Python program. Your task is to read the 
# task descriptions below and then write one or more Python statements to
# carry out the tasks. There's a Python "print" statement before each
# task that will display the expected output for that task; you can use
# this to ensure that your statements are correct.
#

print "------"
print "Task 1: Arithmetic expressions"
print "Expected output: 7"

# Task 1: Add parentheses to the Python statement below so that it prints
# out the number 7.

print (10 + 4) / 2

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

print "\n------"
print "Task 2: Expressions of inequality"
print "Expected output: True"

# Task 2: Change the operator in the statement below so that it displays
# "True" instead of "False."

print 14 < 15

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

print "\n------"
print "Task 3: Variable assignment"
print "Expected output: 32"

# Task 3: Change the variable assignment below so that the print statement
# displays "32." (Don't change the print statement!)

my_number = 32
print my_number

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

print "\n------"
print "Task 4: Types"
print "Expected output: <type 'str'>"

# Task 4: Three variables are assigned below, all with different types.
# Replace the word "None" inside the parentheses of type() in the print
# statement below so that it prints "<type 'str'>".

x = 14
y = 17.4
z = "mother said there'd be days like these"
print type(z)

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

print "\n------"
print "Task 5: String literals"
print "Expected output: We aren't friends now."

# Task 5: Modify the print statement below so that it displays the string
# "We aren't friends now." (i.e., change "are" to "aren't".) Use a
# single quoted string---don't change it to double quotes.

print 'We aren\'t friends now.'

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

print "\n------"
print "Task 6: Questions about strings"
print "Expected output: 51"

# Task 6: After "print" below, write an expression that evaluates to the
# sum of the lengths of the two string variables defined below (first_line
# and second_line). Use the len() function.

first_line = "It was the best of times."
second_line = "It was the worst of times."
print len(first_line) + len(second_line) # your code here!

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

print "\n------"
print "Task 7: Questions about strings, part 2"
print "Expected output: 37"

# Task 7: After "print" below, write an expression that evaluates to the
# position of the word "window" in the string defined in the variable 
# called "romeo." Use the .find() method.

romeo = "But, soft! what light through yonder window breaks?"
print romeo.find('window') # your code here!

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

print "\n------"
print "Task 8: String transformations"
print "Expected output: and the horse you rode in on"

# Task 8: Modify the print statement below so that it prints out the contents
# of the variable "benediction", but with all white space removed from
# the beginning and end of the string. Use the .strip() method.

benediction = "     and the horse you rode in on    \n"
print benediction.strip()

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

print "\n------"
print "Task 9: String transformations, part 2"
print "Expected output: AND THE HORSE YOU RODE IN ON"

# Task 9: Using the previously defined "benediction" variable, write an
# expression after the word "print" below that evaluates to the content
# of the string, with all whitespace removed, and with all letters
# converted to uppercase. Use the .upper() method.

print benediction.upper() # your code here!

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

print "\n------"
print "Task 10: String indexing"
print "Expected output: p"

# Task 10: Modify the value assigned to variable "offset" below so that
# the following "print" statement displays the letter "p".

offset = 1
print "apple"[offset]

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

print "\n------"
print "Task 11: String slices"
print "Expected output: yonder"

# Task 11: Modify the values assigned to variables "start" and "end"
# below so that the following "print" statement displays the word "yonder".

start = 30
end = 36
romeo = "But, soft! what light through yonder window breaks?"
print romeo[start:end]

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

print "\n------"
print "Task 12: Integers and strings"
print "Expected output: 100"

# Task 12: Modify the statement below so that it displays the number 100.
# Do this using the int() function (hint: you need to use it twice).

print int("19") + int("81")

print "\n------"
print "Task 13: List indexes"
print "Expected output: alpha"

# Task 13: A variable "greek" is defined below. The value of this variable
# is of type list. Change the expression below the variable definition so
# that it prints "alpha" (instead of "beta").

greek = ["alpha", "beta", "gamma", "delta", "epsilon"]
print greek[0]

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

print "\n------"
print "Task 14: List slices"
print "Expected output: ['beta', 'gamma', 'delta']"

# Task 14: Change the values of the variables "start" and "finish" below so that
# the print statement displays the second through fourth items in the list
# "greek" (defined above).

start = 1
finish = 3
print greek[start:finish]

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

print "\n------"
print "Task 15: List slices, part 2"
print "Expected output: ['gamma', 'delta']"

# Task 15: Change the value of the variable "foo" below so that the print
# statement displays the last two members of the list "greek" (defined above).
# Use a negative number for "foo".

foo = -2
print greek[foo:]

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

print "\n------"
print "Task 16: List operations"
print "Expected output: True"

# Task 16: Change the value of the variable "letter_to_look_for' below so
# that the print statement displays "True."

letter_to_look_for = "alpha"
print letter_to_look_for in greek

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

print "\n------"
print "Task 17: List operations, part 2"
print "Expected output: ['alpha', 'beta', 'delta', 'epsilon', 'gamma']"

# Task 17: Change the expression below so that the print statement displays
# the list "greek" (defined above) in alphabetical order. (Use the "sorted"
# function.

print sorted(greek)

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

print "\n------"
print "Task 18: Modifying lists"
print "Expected output: ['alpha', 'beta', 'gamma', 'delta', 'epsilon', 'zeta']"

# Task 18: Write a Python statement that adds a new item, "zeta", to the
# list "greek" (defined above). The print statement should display the updated
# list.

# write your statement here
greek.append('zeta')
print greek

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

print "\n------"
print "Task 19: Loops"
print "Expected output:"
print "  alpha"
print "  beta"
print "  gamma"
print "  delta"
print "  epsilon"
print "  zeta"

# Task 19: Write a "for" loop below that prints out each item in the list
# "greek" (defined above). (The list should contain the item that you
# added to the list in task 6.)

for letter in greek:
	print letter


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

print "\n------"
print "Task 20: Loops, part 2"
print "Expected output:"
print "  Alpha"
print "  Beta"
print "  Gamma"
print "  Delta"
print "  Epsilon"
print "  Zeta"

# Task 20: Write a "for" loop below that prints out each item in the list
# "greek" (defined above), but with the first letter of each item capitalized.
# (The list should contain the item that you added to the list in task 6.)

for letter in greek:
	print letter.title()


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

print "\n------"
print "Task 21: Split and join"
print "Expected output:"
print "  81"
print "  9-18-81"

# Task 21: Modify the variable "separator" below so that the first print
# statement displays "81". Modify the variable "glue" so that the second print
# statement displays "9-18-81".

separator = "/"
glue = "-"
parts = "9/18/81".split(separator)
print parts[-1]
print glue.join(parts)

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

print "\n------"
print "Task 22: All together now"
print "Expected output: alpha, beta, gamma, delta, epsilon, zeta, eta, theta"

# Task 22: Make three changes on the Python code below, as follows: (1) replace
# [] with an expression that evaluates to a list with two items, "eta" and
# "theta" (using the .split() method). (2) Replace the word "pass" with a
# Python statement, so that the "for" loop has the effect of adding two new
# items to the list "greek". (Use the .append() method.) (3) Change the value
# of the variable "glue" so that the desired output is displayed.

new_letters = "eta theta"
new_letters_list = new_letters.split(' ') # <-- replace this

for letter_name in new_letters_list:
	greek.append(letter_name)

glue = ", " # <-- and replace this

print glue.join(greek)