Lecture 2 : Application

November, 2021 - updated on April, 2022 - François HU

Master of Science - EPITA

This lecture is available here: https://curiousml.github.io/

Table of contents

• Exercice 1
• Exercice 2
• Exercice 3

Exercice 1: lists

1. Create a list list_ which holds the values $[1, 4, 9, 16, 25, \dots, 400]$. Example:

   >>> list_[0]
   1
   >>> list_[10]
   121
   >>> list_[-1]
   400

2. Create a function inter_in(l, i, j) that swaps the values in position i and j of the list l.

Remark: no need for the function to return an object !

Example:

>>> inter_in(list_, 0, 10)
>>> list_[0]
121
>>> list_[10]
1
>>> inter_in(list_, 0, 10)
>>> list_[0]
1
>>> list_[10]
121

1. Create a function inter_out(l, i, j) that returns a copy of the list l in which the values in positions i and j are swapped. Example:

   >>> clist = inter_out(list_, 0, 10)
   >>> clist[0]
   121
   >>> clist[10]
   1
   >>> list_[0]
   1
   >>> list_[10]
   121

   Hint: Use the method copy of the built-in object list (lists are mutable).

## WRITE IN THIS CELL YOUR CODE WITHOUT ANY ERRORS. YOU SHOULD GENERATE THE LIST: list_
## question 1

## WRITE IN THIS CELL YOUR CODE WITHOUT ANY ERRORS. YOU SHOULD GENERATE THE FUNCTION: inter_in
## question 2

## WRITE IN THIS CELL YOUR CODE WITHOUT ANY ERRORS. YOU SHOULD GENERATE THE FUNCTION: inter_out
## question 3

Exercice 2: dictionaries

We have the following dictionary which contains students grade (don't forget to execute the cell):

# DON'T MODIFY THIS PROGRAM, JUST EXECUTE IT
students = {'Name': ['Arthur',
                     'Marcial',
                     'Margaux',
                     'François',
                     'Julie',
                     'Sophie',
                     'Alex',
                     'Christine'
                    ],
            'Grade': [8, 2, 15, 3, 7, 10, 11, 16]}

The teacher wants to reajust the grades and decides to add 5 points to the grade of each student. For that purpose, follow the following steps:

1. Append and add by 5 each element of the list students['Grade'] in a new list named ugrade

1. In the dictionary students, add a new field named Ugrade with ugrade as an item.

Even after the reajustment, some students have less than 10 points so therefore they need to do a rattrapage examination.

1. Create a new dictionary named retake_examination which contains the Name, Grade and Ugrade of the students who need to retake the examination.

## WRITE IN THIS CELL YOUR CODE WITHOUT ANY ERRORS. YOU SHOULD GENERATE THE LIST: ugrade
## question 1

## WRITE IN THIS CELL YOUR CODE WITHOUT ANY ERRORS. YOU SHOULD UPDATE THE DICITONARY: students
## question 2

## WRITE IN THIS CELL YOUR CODE WITHOUT ANY ERRORS. YOU SHOULD GENERATE THE DICITONARY: retake_examination
## question 3

Exercice 3: strings

1. Create a function signature(text) which returns the string text with " EPITA." at the end. Remark: be careful, we have a space and . in the signature.

Example:

>>> signature('Hello world!')
'Hello world! EPITA.'
>>> signature("Don't be late for the test.")
"Don't be late for the test. EPITA."

1. Create a function delete_signature(text) which returns the string text with " EPITA." at the end deleted. If the substring " EPITA." does not exist, then do nothing. Example:

   >>> delete_signature('Hello world! EPITA.')
   'Hello world!'
   >>> delete_signature("Don't be late for the test.")
   "Don't be late for the test."
   >>> delete_signature('Hello world! EPITA')
   'Hello world! EPITA'

   Hints: a string is a container where:

• we can access to the last 7 characters of a string text with text[-7:];
• we can access to all the characters of a string text except the last 7 characters with text[:-7].

## WRITE IN THIS CELL YOUR CODE WITHOUT ANY ERRORS. YOU SHOULD GENERATE THE FUNCTION: signature
## question 1

## WRITE IN THIS CELL YOUR CODE WITHOUT ANY ERRORS. YOU SHOULD GENERATE THE FUNCTION: delete_signature
## question 2