Exercise Book: Strings, Lists and Dictionaries
Contents
Exercise Book: Strings, Lists and Dictionaries#
This notebook includes a series of exercises that focus on strings, lists, and dictionaries. Through these exercises, emphasis is placed on developing problem-solving skills and intuition on which data structure to use in different scenarios, with the goal of becoming a better programmer.
Exercise 1#
You are tasked to implement a function called format_address(address) that separates out parts of the address string into new strings: house_number and street_name, and returns:
`"house number X on street named Y"`.
The format of the input string is: numeric house number, followed by the street name which may contain numbers, but never by themselves, and could be several words long.
For example:
"123 Main Street", "1001 1st Ave", or "55 North Center Drive".
The function should take in one parameter:
a string addressrepresenting the address to be formatted.
def format_address(address_string):
"""
Parameters:
address_string (str): A string representing the address
with a numerica house number followed by the street name
Returns:
A formatted string containing the house number and
the street name separated by the words
"on street named".
"""
list1 = address_string.split(" ")
house_number = list1[0]
list1.pop(0)
street_number = " ".join(list1)
address_str = "house number {} on street named {}".format(house_number,street_number)
return address_str
# Should print: "house number 123 on street named Main Street"
print("Run 1")
print("Output Returned: {}".format(format_address("123 Main Street")),end="\n\n")
# Should print: "house number 1001 on street named 1st Ave"
print("Run 2")
print(format_address("1001 1st Ave"),end="\n\n")
# Should print "house number 55 on street named North Center Drive"
print("Run 3")
print(format_address("55 North Center Drive"))
Run 1
Output Returned: house number 123 on street named Main Street
Run 2
house number 1001 on street named 1st Ave
Run 3
house number 55 on street named North Center Drive
Exercise 2#
The function replace_domain takes an email address, an old_domain, and a new_domain as arguments. If the email address contains the old_domain, the function replaces it with the new_domain and returns the updated email address. If the email address does not contain the old_domain, the function simply returns the original email address.
def replace_domain(email,old_domain,new_domain):
"""
Parameters:
email (str): The email address to modify
old_domain (str): The domain to replace in the email address
new_domain (str): The new domain to replace the old domain with
Returns:
str: The modified email address with the new domain
"""
if "@" + old_domain in email:
index = email.index("@")
new_email = email[:index] + "@" + new_domain
return new_email
return email
# Input = viktor_pal17@yahoo.com , Expected Output = viktor_pal@google.com
print("Run 1")
print(replace_domain("viktor_pal17@yahoo.com","yahoo.com","google.com"),end="\n\n")
# Input = jesse_roy@google.com, Expected Output = jesse_roy@gmail.com
print("Run 2")
print(replace_domain("jesse_roy@google.com","google.com","gmail.com"),end="\n\n")
Run 1
viktor_pal17@google.com
Run 2
jesse_roy@gmail.com
Exercise 3#
You are given three lists: drews_list, jamies_list, and professors_list. The two lists, drews_list and jamies_list contain the names of the students in the order they arrived in the classroom. The professor needs to combine drews_list and jamies_list into one list in the order that the students arrived.
However, Jamie’s list is in reverse order, so you need to reverse it before combining it with Drew’s list. Write a function named combine_lists to take in the two lists and return the combined list in the correct order.
Input:
drews_list (list): A list of strings containing the names of students in the order they arrived in the classroom. Length is n.
jamies_list (list): A list of strings containing the names of students in reverse order that Jamie noted. Length is m.
Output:
Returns a list of strings containing the names of students in the order they arrived in the classroom. The length of the combined list should be n + m.
def combine_lists(list1,list2):
"""
Parameters:
list1 (list): A list of strings containing the name of students in
the reverse order that Jamie noted
list2 (list): A list of strings containing the name of students in
the order they arrived in the classroom
Return:
final_list (list): A list of strings containing the names of students
in the order they arrived in the classroom.
"""
first_list = list2
second_list = []
length_list1 = len(list1)
count = -1
for index in range(length_list1):
student_name = list1[count]
second_list.append(student_name)
count -= 1
if abs(count) > length_list1:
break
final_list = first_list + second_list
return (final_list)
Jamies_list = ["Alice", "Cindy", "Bobby", "Jan", "Peter"]
Drews_list = ["Mike", "Carol", "Greg", "Marcia"]
print("Jamies' List: {}".format(Jamies_list))
print("Drews' List: {}".format(Drews_list),end="\n\n\n")
print("Run 1")
print("Expected Output: ['Mike', 'Carol', 'Greg', 'Marcia', 'Peter', 'Jan', 'Bobby', 'Cindy', 'Alice']")
print("Output Returned: {}".format(combine_lists(Jamies_list, Drews_list)))
Jamies' List: ['Alice', 'Cindy', 'Bobby', 'Jan', 'Peter']
Drews' List: ['Mike', 'Carol', 'Greg', 'Marcia']
Run 1
Expected Output: ['Mike', 'Carol', 'Greg', 'Marcia', 'Peter', 'Jan', 'Bobby', 'Cindy', 'Alice']
Output Returned: ['Mike', 'Carol', 'Greg', 'Marcia', 'Peter', 'Jan', 'Bobby', 'Cindy', 'Alice']
Exercise 4#
You are tasked with combining two dictionaries, containing information about the guests attending a party hosted by Taylor and Rory. The two dictionaries are named taylor_guests and rory_guests.
taylor_guests contains partial information about the guests attending the party, where the key is the name of the guest and the value is the number of guests the guest is bringing. rory_guests also contains similar information but with more current and updated data about the guests.
Write the code to combine both dictionaries into one, with each friend listed only once, and the number of guests from rory_guests taking precedence, if a name is included in both dictionaries. Finally, print the resulting dictionary.
Note
taylor_guestscontains 2 guests for “Alice” whilerory_guestscontains guest for “Alice”. Therefore, the combined dictionary contains “Alice” with 1 guest, taking the value fromrory_guests.
def combine_guests(guests1,guests2):
"""
Parameters:
taylor_guests (dict): A dictionary with names of guests as keys and the
number of guests each friend is bringing as values
rory_guests (dict): A dictionary with names of guests as keys and the
number of guests each friend is bringing as values
Returns:
A dictionary with each friend listed only once, and the number of guests
rory_guests taking precedence, if a name is included in both dictionaries
"""
# guests1 represents Rory's list
# guests2 represents Taylor's list
final_dict = {}
r_guestlist = list(guests1.keys())
t_guestlist = list(guests2.keys())
actual_guestlist = r_guestlist + t_guestlist
for names in actual_guestlist:
if names in guests1:
peeps_they_bring = guests1[names]
final_dict[names] = peeps_they_bring
elif names in guests2:
peeps_they_bring = guests2[names]
final_dict[names] = peeps_they_bring
if names in t_guestlist and names in r_guestlist:
b = guests1[names]
final_dict[names] = b
return final_dict
Rorys_guests = { "Adam":2, "Brenda":3, "David":1, "Jose":3, "Charlotte":2, "Terry":1, "Robert":4}
Taylors_guests = { "David":4, "Nancy":1, "Robert":2, "Adam":1, "Samantha":3, "Chris":5}
print("Rory's Guest List: {}".format(Rorys_guests))
print("Taylor's Guest List: {}".format(Taylors_guests),end="\n\n\n")
print("Run 1")
print(combine_guests(Rorys_guests, Taylors_guests))
Rory's Guest List: {'Adam': 2, 'Brenda': 3, 'David': 1, 'Jose': 3, 'Charlotte': 2, 'Terry': 1, 'Robert': 4}
Taylor's Guest List: {'David': 4, 'Nancy': 1, 'Robert': 2, 'Adam': 1, 'Samantha': 3, 'Chris': 5}
Run 1
{'Adam': 2, 'Brenda': 3, 'David': 1, 'Jose': 3, 'Charlotte': 2, 'Terry': 1, 'Robert': 4, 'Nancy': 1, 'Samantha': 3, 'Chris': 5}
Exercise 5#
You are given an input string, and your task is to write a function count_letters(string) to count the frequency of letters in the input string. The output should be a dictionary where the keys are the lowercase letters that appear in the string, and the values are the frequency of those letters.
Note:
Only letters should be counted, not blank spaces, numbers, or punctuation.
Upper case should be considered the same as lower case.
def count_letters(text):
"""
Parameters:
text (str): A string of length n containing letters, blank spaces,
numbers and punctuation
Return:
A dictionary where the keys are lowercase letters that appear
in the input string, and the values are the frequency of
those letters.
"""
result = {}
text_lower = text.lower()
text_in_list = text_lower.split()
for words in text_in_list:
for letter in words:
if letter.isalpha():
count = 1
if letter not in result:
result[letter] = count
else:
character = result[letter]
count = character + 1
result[letter] = count
return result
# Should be {'a': 2, 'b': 2, 'c': 2}
print("Run 1")
print("Output: {}".format(count_letters("AaBbCc")),end="\n\n")
# Should be {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}
print("Run 2")
print("Output: {}".format(count_letters("Math is fun! 2+2=4")),end="\n\n")
# Should be {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
print("Run 3")
print("Output: {}".format(count_letters("This is a sentence.")),end="\n\n")
Run 1
Output: {'a': 2, 'b': 2, 'c': 2}
Run 2
Output: {'m': 1, 'a': 1, 't': 1, 'h': 1, 'i': 1, 's': 1, 'f': 1, 'u': 1, 'n': 1}
Run 3
Output: {'t': 2, 'h': 1, 'i': 2, 's': 3, 'a': 1, 'e': 3, 'n': 2, 'c': 1}
Exercise 6#
Create a program that reads integers from the user until a blank line is entered.
Once all of the integers have been read, your program should display all of the negative numbers, followed by all of the zeros, followed by all of the positive numbers.
Within each group the numbers should be displayed in the same order that they were entered by the user.
For example, if the user enters the values:
3, -4, 1, 0, -1, 0 and -2
Then your program should output the values:
-4, -1, -2, 0, 0, 3 and 1
Your program should display each value on it’s own line.
# Generating a list
user_list = []
flag = True
while flag:
user_in = input("Enter a number: ")
if user_in == "":
flag = False
else:
user_list.append(int(user_in))
Enter a number: 3
Enter a number: -4
Enter a number: 1
Enter a number: 0
Enter a number: -1
Enter a number: 0
Enter a number: -2
Enter a number:
def list_group(input_list):
"""
Group a list of numbers into three categories: negatives, zeros and positives.
Parameters:
input_list (list) : list of int or float
Returns:
A new list with the same numbers as `input_list`, but sorted into three
sub-lists in this order: negatives, zeros, positives.
"""
negative_list = []
zero_list = []
positive_list = []
output_list = []
for ele in input_list:
if ele < 0:
negative_list.append(ele)
elif ele == 0:
zero_list.append(ele)
else:
positive_list.append(ele)
output_list.extend(negative_list)
output_list.extend(zero_list)
output_list.extend(positive_list)
return output_list
ordered_list = list_group(user_list)
# Expected output = [-4, -1, -2, 0, 0, 3, 1]
print("Run 1")
print('Initial list: {} | Ordered list: {}'.format(user_list,ordered_list))
Run 1
Initial list: [3, -4, 1, 0, -1, 0, -2] | Ordered list: [-4, -1, -2, 0, 0, 3, 1]
Exercise 7#
A proper divisor of a positive integer (n) is a positive integer less than (n) which divides evenly into n.
Write a function that computes all of the proper divisors of a positive integer. The integer will be passed to the function as it’s only parameter.
The function will return a list containing all of the proper divisors as its only result. Complete this exercise by writing a main program that demonstrates the function by reading a value from the user and displaying the list of its proper divisors. Ensure that your main program only runs when your solution has not been imported into another file.
def proper_divisors(n):
"""
Parameters:
n (int) - positive integer
Returns:
divisor_list - A list containing all of the
proper divisors of n
"""
divisor_list = []
for value in range(1,n):
if (n % value) == 0:
divisor_list.append(value)
return divisor_list
print("Proper Divisors for numbers 1 - 50",end = "\n\n")
for run in range(1,51):
print("{} | {}".format(run,proper_divisors(run)))
Proper Divisors for numbers 1 - 50
1 | []
2 | [1]
3 | [1]
4 | [1, 2]
5 | [1]
6 | [1, 2, 3]
7 | [1]
8 | [1, 2, 4]
9 | [1, 3]
10 | [1, 2, 5]
11 | [1]
12 | [1, 2, 3, 4, 6]
13 | [1]
14 | [1, 2, 7]
15 | [1, 3, 5]
16 | [1, 2, 4, 8]
17 | [1]
18 | [1, 2, 3, 6, 9]
19 | [1]
20 | [1, 2, 4, 5, 10]
21 | [1, 3, 7]
22 | [1, 2, 11]
23 | [1]
24 | [1, 2, 3, 4, 6, 8, 12]
25 | [1, 5]
26 | [1, 2, 13]
27 | [1, 3, 9]
28 | [1, 2, 4, 7, 14]
29 | [1]
30 | [1, 2, 3, 5, 6, 10, 15]
31 | [1]
32 | [1, 2, 4, 8, 16]
33 | [1, 3, 11]
34 | [1, 2, 17]
35 | [1, 5, 7]
36 | [1, 2, 3, 4, 6, 9, 12, 18]
37 | [1]
38 | [1, 2, 19]
39 | [1, 3, 13]
40 | [1, 2, 4, 5, 8, 10, 20]
41 | [1]
42 | [1, 2, 3, 6, 7, 14, 21]
43 | [1]
44 | [1, 2, 4, 11, 22]
45 | [1, 3, 5, 9, 15]
46 | [1, 2, 23]
47 | [1]
48 | [1, 2, 3, 4, 6, 8, 12, 16, 24]
49 | [1, 7]
50 | [1, 2, 5, 10, 25]
Exercise 8#
An integer (n) is said to be perfect when the sum of all of the proper divisors of (n) is equal to (n).
For example:
28 is a perfect number because it's proper divisors
are 1, 2, 4, 7, 14 and 1 + 2 + 4 + 7 + 14 = 28
Write a function that determines whether or not a positive integer is perfect. Your function will take one parameter. If that parameter is a perfect number, then your function will return true. Otherwise, it will return false.
In addition, write a main program that uses your function to identify and display all of the perfect numbers between 1 and 10,000.
Import your solution to previous exercise when completing this task.
def perfect_number(input_number):
"""
Parameters:
input_number (int): a number to check whether it's a perfect number
Returns:
True if the parameter turns out to be perfect number, else
False
"""
divisor_list = proper_divisors(input_number)
the_sum = sum(divisor_list)
if the_sum == input_number:
return True
else:
return False
perfect_numlist = []
for j in range(1,10001):
if perfect_number(j):
#print("{}: Yes".format(j))
perfect_numlist.append(j)
print("Here is a list of perfect numbers between 1 and 10,000: \n{}\n\n".format(perfect_numlist))
print("For the first 10,000 positive integers, only {}% are perfect numbers".format(len(perfect_numlist)/10000 * 100))
Here is a list of perfect numbers between 1 and 10,000:
[6, 28, 496, 8128]
For the first 10,000 positive integers, only 0.04% are perfect numbers
Exercise 9#
Write a program that reads numbers from the user until a blank line is entered. Your program should display the average of all of the values entered by the user.
Then the program should display all of the below average values, followed by all of the average values (if any), followed by all of the above average grades. An appropriate label should be displayed before each list of values.
the_avg = 0
flag = True
store_list = []
while flag:
user_in = input("Enter a number: ")
if user_in != "":
store_list.append(float(user_in))
else:
flag = False
the_avg = sum(store_list) / len(store_list)
below_average = []
just_average = []
above_average = []
for val in store_list:
if val < the_avg:
below_average.append(val)
elif val == the_avg:
just_average.append(val)
else:
above_average.append(val)
Enter a number: 44
Enter a number: 47
Enter a number: 49
Enter a number: 51
Enter a number: 53
Enter a number: 56
Enter a number:
print("Average value: {}".format(the_avg))
print("Numbers below average: {}".format(below_average))
print("Numbers equal to average: {}".format(just_average))
print("Numbers above average: {}".format(above_average))
Average value: 50.0
Numbers below average: [44.0, 47.0, 49.0]
Numbers equal to average: []
Numbers above average: [51.0, 53.0, 56.0]
Exercise 10#
Two words are anagrams if they contain all of the same letters, but in a different order.
For example, evil and live are anagrams because
each contains one ‘e’, one ‘v’, one ‘i’ and one ‘l’.
Create a program that reads two strings from the user, determines whether or not they are anagrams, and reports the result.
def check_anagram(str1,str2):
"""
Check if two input strings are anagrams of each other.
Parameters:
str1 (str): First input string.
str2 (str): Second input string.
Returns:
bool: True if the input strings are anagrams of each other, False otherwise.
int: -1 if the input strings are of different lengths.
"""
str1 = str1.lower()
str2 = str2.lower()
if len(str1) == len(str2):
dict1 = {}
dict2 = {}
for k in range(len(str1)):
char1 = str1[k]
char2 = str2[k]
if char1 not in dict1:
dict1[char1] = 1
else:
dict1[char1] = dict1[char1] + 1
if char2 not in dict2:
dict2[char2] = 1
else:
dict2[char2] = dict2[char2] + 1
if dict1 == dict2:
return True
else:
return False
else:
return -1
print("Run 1",end="\n\n\n")
user_str1 = input("Enter a string: ")
user_str2 = input("Enter another string: ")
is_anagram = check_anagram(user_str1,user_str2)
if is_anagram == True:
print("\n'{}' and '{}' are anagrams".format(user_str1,user_str2))
elif is_anagram == -1:
print("\nString lengths different, invalid entry")
else:
print("\n'{}' and '{}' are not anagrams".format(user_str1,user_str2))
Run 1
Enter a string: Anfield
Enter another string: Delfina
'Anfield' and 'Delfina' are anagrams
print("Run 2",end="\n\n\n")
user_str1 = input("Enter a string: ")
user_str2 = input("Enter another string: ")
is_anagram = check_anagram(user_str1,user_str2)
if is_anagram == True:
print("\n'{}' and '{}' are anagrams".format(user_str1,user_str2))
elif is_anagram == -1:
print("\nString lengths different, invalid entry")
else:
print("\n'{}' and '{}' are not anagrams".format(user_str1,user_str2))
Run 2
Enter a string: summertime
Enter another string: winter
String lengths different, invalid entry
print("Run 3",end="\n\n\n")
user_str1 = input("Enter a string: ")
user_str2 = input("Enter another string: ")
is_anagram = check_anagram(user_str1,user_str2)
if is_anagram == True:
print("\n'{}' and '{}' are anagrams".format(user_str1,user_str2))
elif is_anagram == -1:
print("\nString lengths different, invalid entry")
else:
print("\n'{}' and '{}' are not anagrams".format(user_str1,user_str2))
Run 3
Enter a string: hat
Enter another string: cat
'hat' and 'cat' are not anagrams