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Goals

  • Understanding fundamentals of Python programming:
  • Variables, data types, lists, sets and tuples.
  • Conditional expressions and loops
  • Sort
  • Dictionary
  • Files and user interaction

Exercise 1

1. Comments

# This is a comment
print("Bonjour")

2. Variables

# a variable
message = "le monde!"
print(message)

a = 10
b = 20
c = a + b
print(c)

# floating point numbers
pi = 3.14
print(pi)

# data types
message1 = "Bonjour"
a = 12
pi = 3.14
print(type(message1))
print(type(a))
print(type(pi))

3. Concatenation of two strings

# concatenation of two strings
message = "le monde!"
print("Bonjour" + message)

# concatenation of two strings
message1 = "Bonjour "
message2 = "le monde!"
print(message1 + message2)

# concatenation involving two variables of different data types
# operation + on two different data types

#Uncomment the print statement and run the code
message1 = "Bonjour en Python"
a = 3
#print(message1 + a)

Why did you get this error? In the following code, we correct this error.

# concatenation solution involving two variables of different data types
message1 = "Bonjour en Python "
a = 3
print(message1 + str(a))

4. Lists

a = [10, 20, 30, 40, 50]
print(a)

a = [10, 20, 30, 40, 50]
print(a[0])
print(a[1])
print(a[2])
print(a[3])
print(a[4])

#Uncomment the print statement and run the code
a = [10, 20, 30, 40, 50]
#print(a[8])

Why did you get this error? We are trying to access a element at an index that does not exist.

message1 = "Bonjour en Python "
print(message1[0])
print(message1[1])
print(message1[2])
print(message1[3])
print(message1[4])
print(message1[5])
print(message1[6])
print(message1[7])

The above code displayed the individual characters in the string (or list of characters). We will now get the length of this string.

message1 = "Bonjour en Python "
print(len(message1))

We are now goint to create a list of integers.

a = [10, 20, 30, 40, 50]
print(len(a))

a = [10, 20, 30, 40, 50]

# add a new number at the end of the list
a.append(60)
print(a)

a = [10, 20, 30, 40, 50]

# modify a number at a particular index
a[0] = 0
print(a)

Why did we get this error? We are modifying an element at a non-existing index.

#Uncomment the assignment statement and run the code
a = [10, 20, 30, 40, 50]
#a[6] = 20
print(a)

a = [10, 20, 30, 40, 50]

# inserting an element at a particular index will modify the list
a.insert(0, 0)
print(a)
print(len(a))

a = [10, 20, 30, 40, 50]
a.insert(6,60)
print(a)
print(len(a))

a = [10, 20, 30, 40, 50]

# We will now try to insert a number at an index greater than the length
# of the list. We will see that we do not get any error and the new number
# is added at the end of the list
a.insert(10,60)
print(a)
print(len(a))

5. Tuples (non-modifiable lists)

a = (10, 20, 30, 40, 50)
print(a)

a = (10, 20, 30, 40, 50)
print(a[0])

a = (10, 20, 30, 40, 50)

# We now try to modify a tuple
# Uncomment the code below and run the code
# A tupe is a non-modifiable list

#a[0] = 0
print(a)

6. Sets

# A set is a collection of distinct elements
a = {10, 20, 30, 40, 50, 10, 20, 30, 40, 50}
print(a)

a = {10, 20, 30, 40, 50, 10, 20, 30, 40, 50}
a.add(10)
print(a)

a = {10, 20, 30, 40, 50, 10, 20, 30, 40, 50}
a.add(60)
print(a)

a = {10, 20, 30, 40, 50, 10, 20, 30, 40, 50}
a.remove(40)
print(a)

We will now try different data types with the numbers and print the result

# set
a = {10, 20, 30, 40, 50, 10, 20, 30, 40, 50}
print(a)
print(type(a))
 
# tuple
b = (10, 20, 30, 40, 50, 10, 20, 30, 40, 50)
print(b)
print(type(b))
 
# list
c= [10, 20, 30, 40, 50, 10, 20, 30, 40, 50]
print(c)
print(type(c))

Exercise 2

1. Conditional Expressions

a = 12
if( a%2 == 0):
    print(a, " is divisible by 2")
else:
    print(a, " is not divisible by 2")

lang = "Français"
if (lang =="Français"):
    print("Bonjour le monde!")
else:
    print("Hello World!")

2. Loops

Loops can also be used to access the elements at different indices.

for i in [10, 20, 30, 40, 50, 10, 20, 30, 40, 50]:
    print(i)

for i in (10, 20, 30, 40, 50, 10, 20, 30, 40, 50):
    print(i)

for i in {10, 20, 30, 40, 50, 10, 20, 30, 40, 50}:
    print(i)

2. Range

for i in range(0,10):
    print(i)

for i in range(0,10,2):
    print(i)

# print() by default displays the message followed by a new line
# But you can change its behaviour
for i in range(0,10,2):
    print(i, end=' ')

for i in range(10,0,-2):
    print(i)

for i in range(10,0):
    print(i)

split(): the function can be used to separate a string using a specified delimited. By default, the delimiter is a white space.

for i in "Bonjour,le,monde!".split():
    print(i)

for i in "Bonjour,le,monde!".split(","):
    print(i)

Write a program in Python to display the following output

1

12

123

1234

12345

123456

1234567

12345678

Exercise 3

1. Sort

num = [10, 20, 30, 40, 50, 10, 20, 30, 40, 50]
num.sort()
print(num)

2. Sort (decreasing order)

num = [10, 20, 30, 40, 50, 10, 20, 30, 40, 50]
num.sort(reverse=True)
print(num)

3. minimum

num = [10, 20, 30, 40, 50, 10, 20, 30, 40, 50]
print(min(num))

4. maximum

num = [10, 20, 30, 40, 50, 10, 20, 30, 40, 50]
print(max(num))

5. sorted()

You can use the function if you do not wish to modify your initial list by sorting.

num = [70, 20, 30, 10, 50, 60, 20, 80, 70, 50]
sortednum = sorted(num,reverse=True)
print(num)
print(sortednum)

num = [70, 20, 30, 10, 50, 60, 20, 80, 70, 50]

# select first five numbers
sortednum = sorted(num,reverse=True)[:5]
print(sortednum)

Modify the code given below to display the five greatest unique numbers.

print(sorted("Bonjour le monde!".split(), key=str.lower, 
           reverse=True))

Exercise 4

1. Dictionary

a = {"contente": 12, "content": 12, "triste": 2}
print(a)
print(type(a))

a = {"contente": 12, "content": 12, "triste": 2}
for key in a:
    print("la phrase ", key, " apparait ", a[key], " fois")

a = {"contente": 12, "content": 12, "triste": 2}
for key,value in a.items():
    print("la phrase ", key, " apparait ", value, " fois")
  



a = {"contente": 12, "content": 12, "triste": 2}
a["joie"] = 10
print(a)
  



a = {"contente": 12, "content": 12, "triste": 2}
del a["triste"]
print(a)

mots = {"contente": 12, "content": 12, "triste": 2, 
     "joie" : 10}
print(sorted(mots))

mots = {"contente": 12, "content": 12, "triste": 2, 
     "joie" : 10}
mots_tuple = [(key, value) for key,value in mots.items()]
print(mots_tuple)

2. itemgetter

from operator import itemgetter
 
mots = {"contente": 12, "content": 12, "triste": 2, 
     "joie" : 10}
mots_tuple = [(key, value) for key,value in mots.items()]
print(sorted(mots_tuple, key=itemgetter(1)))

3. Interaction with user

nom = input("Quel est votre nom?")
print(nom)

age = input("Quel est votre âge? ")
print(age)
print(type(age))

age = input("Quel est votre âge? ")
age = int(age)
print(age)
print(type(age))

Question: Write a program in Python that interacts with the user to obtain the following information of 5 students:

  • Name of student
  • Age
  • Grades in 5 modules

Once the information for all the five students is obtained, calculate and display the following values for every module:

  • average grade
  • maximum grade
  • minimum grade

Exercise 5

1. Files

message = "Bonjour le monde"
with open("bonjour.txt", "w") as file:
    file.write(message)
file.close()

with open("bonjour.txt", "r") as file:
    text = file.read()
    print(text)
file.close()

message1 = "Bonjour le monde"
message2 = "Programmation en Python"
with open("bonjour.txt", "w") as file:
    file.write(message1)
    file.write(message2)
file.close()

with open("bonjour.txt", "r") as file:
    text = file.read()
    print(text)
file.close()

message1 = "Bonjour le monde\n"
message2 = "Programmation en Python"
with open("bonjour.txt", "w") as file:
    file.write(message1)
    file.write(message2)
file.close()
 
with open("bonjour.txt", "r") as file:
    text = file.read()
    print(text)
file.close()

2. readline()

This function can be used to read a file line by line and not the complete content in a single call like read()

message1 = "Bonjour le monde\n"
message2 = "Programmation en Python"
with open("bonjour.txt", "w") as file:
    file.write(message1)
    file.write(message2)
file.close()

with open("bonjour.txt", "r") as file:
    text = file.readline()
    print(text)
file.close()

message1 = "Bonjour le monde\n"
message2 = "Programmation en Python\n"
with open("bonjour.txt", "w") as file:
    file.write(message1)
    file.write(message2)
file.close()

with open("bonjour.txt", "r") as file:
    for line in file:
        print(line)
file.close()

Question: Copy any HTML file in your home directory. Write a program in Python to get the following values:

  • number of characters in the HTML file
  • number of lines in the HTML file
  • number of words in the HTML file
  • first twenty words in the HTML file
  • distinct words in the HTML file

Question: Copy the CSV file population.csv from the data folder. The file contains the population values between 1901 and 2016. Write a program in Python to get the maximum value.

  • the maximum value of population
  • the minimum value of population