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དཔལ་ལྡན་འབྲུག་གཞུང་། ཤེས་རིག་དང་རིག་རྩལ་གོང་འཕེལ་ལྷན་ཁག།

Department of School Education

Ministry of Education & Skills Development

Python Coding

January 2024

Class X ICT Curriculum

January 2024

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Key stage IV

Class X

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DATA STRUCTURE - DICTIONARY

Key Concept # 6

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Main concepts

Sub - concepts

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Dictionary

  • Introduction to Dictionary
    • Definition
    • Characteristics
    • Creating a dictionary
  • Accessing elements of Dictionary
  • Traversing the elements of Dictionary
  • Dictionary methods
  • clear(), copy(), pop(), get(), items(), update(), values()

Concept Overview

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  • Explain dictionary in Python program.
  • Describe the key characteristics of dictionary.
  • Create, store and manipulate items in dictionary.
  • Iterate over dictionary items using for loop.
  • Create Python programs that solve a real-world problem using dictionaries.

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Objectives

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DICTIONARY

ACTIVITIES

  1. Understanding Dictionary
  2. Demo 1 -Personal Digital Assistant
  3. Activity 1 - Information About the Car
  4. Demo 2 - Dictionary Methods
  5. Activity 2 - Writing the Output
  6. Activity 3 - Storing Students Percentage
  7. Activity 4 - Deleting Elements
  8. Activity 5 - Check your Understanding
  9. Activity 6 - Writing the Output
  10. Activity 7 - Modifying the Dictionary

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Understanding Dictionary

  • A dictionary is a collection of data that stores in key-value pairs.
  • It allow us to associate a value to a unique key, and then to quickly access this value.
  • It is ordered, changeable and do not allow duplicate key.
  • It is created using {} or dict() function.

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dict_name={key_1:value_1,key_2:vlaue_2,...}

Syntax

std_info={'roll_no':1,'name':'Pema','Class':10}

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Example

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Characteristics of Dictionaries

Ordered

Dictionaries are ordered, which means that the items have a defined order, and that order will not change.

Unique

Each value in a dictionary has a Key and keys in dictionaries should be unique.

Mutable

The dictionaries are changeable collections, which implies that we can add or remove items after the creation.

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Demo 1 - Personal Digital Assistant

Write a Python program that acts as personal digital assistant, storing name, class and roll number of a student.

name - Karma, class- X, roll_number- 5

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info = {"name":"Karma","class":"X","roll_number": 5}

print(info)

Code

Output

{"name":"Karma","class":"X","roll_number": 5}

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Activity 1 - Information About the Car

Write a Python program to create a dictionary with the following

informations about the car. Then display the items in the dictionary in

the screen.

Brand - Ford, model - Mustang, year - 1964

Your time! ………………. Solve it

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Adding elements into the Dictionary

  • A new dict element can be added by inserting a new key value.
  • The new key value should be unique. Otherwise, old value will be replaced.

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biodata = {‘name’:’Karma’,’school’:’BHSS’}

print()

biodata[‘DOB’]= “12/2/2023”#adding DOB to the dict.

print(biodata)

Code

dictionary_name[‘key_name’]=”value”

Syntax

Output

{‘name’:’Karma’,‘school’:’ZMSS’,’DOB’:’12/2/2023’}

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Accessing elements in the Dictionary

  • In dictionary, items can be accessed by referring to its key name, inside square brackets:

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dictionary_name[‘key_name’]

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Syntax

Code

Output

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std_info={'roll_no':1,'name':'Pema','Class':'X'}

print(std_info['name'])

Pema

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Activity 1 - Creating a Dictionary

  1. Write a Python program to create a dictionary with your progress report such as Name, Class,Percentage and rank. Then display the result.

Now, check your understanding!

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Activity 1 - Creating a Dictionary (cont.)

  1. Add new item SUPW grade in the dictionary created in the above question 1.

Additional testing>>>

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Activity 1 - Creating a Dictionary (cont.)

  1. Display only the name and percentage of the student from the dictionary created in the previous question 1.

Some more………………………………..

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Dictionary Methods

Python has a set of built-in methods that can use on dictionaries. Here are some of the common dictionary methods in Python:

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Sl. No

Method

Description

Syntax

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clear()

Remove all elements from the dictionary.

dictionary.clear()

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copy()

get()

Returns a copy of the dictionary.

Returns the value of the specified key.

value = dictionary.get(‘key’)

new_dict = dictionary.copy()

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Dictionary Methods(cont.)

Sl. No

Method

Description

Syntax

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pop()

items()

keys()

Removes the element with the specified key.

Returns a list containing the dictionary's keys.

Returns a list containing a tuple for each key value pair.

dictionary.items()

dictionary.keys()

value = dictionary.pop(‘key’)

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Dictionary Methods(cont.)

Sl. No

Method

Description

Syntax

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update()

values()

Updates the dictionary with the specified key-value pairs.

Returns a list of all the values in the dictionary.

dictionary.values()

dictionary.update({‘Key’: ‘Value’})

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Demo 2 - Dictionary Methods

Using the data given below,create dictionary data structures and practice the dictionary methods.

keys = a,b,c

values = 1,2,3

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my_dict = {"a": 1, "b": 2, "c": 3}#creating dictionary

print("Original dictionary",my_dict)

OP: Original dictionary {'a': 1, 'b': 2, 'c': 3}

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print(my_dict.get("a"))

OP: 1

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print(my_dict.items())

OP: dict_items([('a', 1), ('b', 2), ('c', 3)])

Code

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print(my_dict.values())

OP: dict_values([1, 2, 3])

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value = my_dict.pop("a")

print(value)

OP: {'b': 2, 'c': 3}

keys_view = my_dict.keys()

print(keys_view)

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Code

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Demo 2 - Dictionary Methods(cont.)

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# Convert the view object to a list for easier display

keys_list = list(keys_view)

print(keys_list)

values_view = my_dict.values()

# Convert the view object to a list for easier display

values_list = list(values_view)

print(values_list)

my_dict.update([("b", 3), ("c", 4)])

print(my_dict)

new_dict = my_dict.copy()

print("New Dictionary",new_dict)

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Demo 2 - Dictionary Methods(cont.)

Output

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['b', 'c']

[2, 3]

{'b': 3, 'c': 4}

New Dictionary {'b': 3, 'c': 4}

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Activity 2 - Writing the Output

Tell your answerS ……………………..

Output

Write output for the Python program given below:

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person ={"name": "Deki", "Dzongkhag":"Haa","Village": "Bongo"}

print(person['name'])

print(person.get('Village'))

print(person.values())

print(person)

Code

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Traversing through a Dictionary

  • Traversing the elements of the dictionary is the systematic process of moving through each item to perform operation on key-value pair.
  • key-value can be traversed using both for and while loops.

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Key value

Types of accessing element of dictionary

item()

methods

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Traversing through the Key Values

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color

fruit

pet

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my_fav ={"color":"blue","fruit": "apple", "pet": "dog"}

for values in my_fav:

print(values)

Code

for key in dict_name:

print(key)

Syntax

Output

for loop iterates over the keys of the dictionary and prints each key on a new line.

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Traversing using the items() method

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color -> blue

fruit -> apple

pet -> dog

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my_fav={"color": "blue", "fruit": "apple", "pet": "dog"}

for key,value in my_fav.items():

print(key, "->",value)

Code

for key, value in dict_name.items():

print(key,value)

Syntax

Output

items() will access both key and value and store them in key and value respectively in each iteration.

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Activity 3 - Storing Students Percentage

Write a Python program that ask the user total number of student and their names and percentage respectively .Display the result of each student.

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Slove the problem .............................

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Deleting a Dictionary Element

  • The dictionary's elements can be deleted by referring to a key value using the del keyword or by using the pop method.
  • The pop() method removes the item with the specified key name.

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Biodata = {‘name’:’Karma’,’school’:’BHSS’}

del Biodata[‘name’]#deleting karma from the dict

Biodata.pop(‘school’)

print(Biodata) #{‘school’:’BHSS’}

Code

del variable_name[key_value]#using del keyword

variable_name.pop(key_value)#using pop method

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Syntax

Output

{}

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Activity 4 - Deleting Elements

{'Brand': 'Ford'}

The provided Python program contains some errors. Debug and rewrite the program to ensure it produces the correct output.

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car ={"brand": "Ford", "model": "Mustang", "year": 1964}

car.pop("Mustang")

del “year”

print(car)

Code

Output

model

car[“year”]

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Updating a Dictionary element

{'name': 'Sangay', 'school': 'BHSS'}

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The dictionary's elements can be updated by referring to a key_value or by using the update() method.

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Biodata = {‘name’:’Karma’,’school’:’BHSS’}

Biodata[‘name’]= “Sangay”#Updating name Sangay

print(biodata)

Code

variable_name[key_Value] = value#using key_value

dict_name.update({"key": "Value"}) #using update method

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Syntax

Output

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Activity 5 - Check your Understanding

Answer the following questions.

  1. How do you remove a key-value pair from a dictionary?

a) Using the remove() method

b) By setting the value to None

c) With the delete() function

d) Using the del keyword

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  1. Which of the following statements is Not true about dictionary keys?

a) Dictionary keys must be unique

b) Dictionary keys can be repeated

c) Dictionary keys are case-sensitive

d) Dictionary keys can be integers

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Activity 5 - Check your Understanding(cont.)

3. How can you check if a value is present in the values of a dictionary?

a) Using the exists() method

b) With the contains() function

c) Using the has_value() method

d) By using the in keyword with values()

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4. What happens if you try to access a key that does not exist in a dictionary?

a) It returns None

b) It raises a KeyError

c)It returns an empty string

d) It appends the key to the dictionary

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Activity 5 - Check your understanding(cont.)

5. Fill in the blanks with appropriate word(s)

  1. A Python dictionary is a collection of __________pairs.
  2. In Python, a dictionary is created using curly braces, and each key-value pair is separated by a ________.
  3. The _________ method is used to add or update key-value pairs in a dictionary.
  4. To remove a key-value pair from a dictionary, you can use the del keyword or the ______ method.
  5. The _______ method returns a list of all values in a dictionary.

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key-value

comma

update()

pop()

values

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Activity 6 - Writing the Output

Use the dictionary given below to answer the questions that follow.

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biodata = {

“Name”: “Jigme Wangmo”,

“Class”: “IX”,

“Age”: 16

“Village”: “Bidung”

}

  1. Write a python code that prints the value of the key Age.
  2. Write a python code that prints the number of items in the dictionary.
  3. Write a python code that prints a list containing the dictionary's keys.

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Activity 6 - Solution

Time to solve >>>> use IDLE or online IDLE compiler

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Activity 7 - Modifying Dictionary

Study the code given below and follow the instruction to achieve the final output:

std_bio_data={“Name”:”Pelden”,”village”:”Bhur”,

”mobile_no”:17485978, “Eng”:98,”Dzo”:99,”Math”:89}

Instructions:

  1. Change the Name value to "Tshewang".
  2. Modify the village name to "Gelephu".
  3. Remove the mobile number entry.
  4. Add a new entry with the key "school" and value "Tashigang MSS".
  5. Calculate the total marks of the student.
  6. Display all keys and values using a for loop, including the total marks.

Homework: You will see same question in Google classroom. Solve and submit in google � classroom.

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  • A dictionary stores data in key-value pairs, allowing efficient and fast access to values using unique keys.
  • Dictionaries are defined using curly braces {} and consist of key-value pairs separated by commas.
  • Similar to lists, dictionaries support operations like insertion, removal, updating, and access using various functions and methods.
  • Accessing values in a dictionary is done using keys. Keys act as unique identifiers for each value.
  • Functions and methods such as clear(), copy(), pop(), get(), items(), update(), values() can be used to manipulate dictionary elements.

Key Points

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Open Google classroom and click on Dictionary-Quiz.

Instructions:

  • You can attempt only once.
  • You will be given 10 minutes only to complete the Quiz.
  • After completing don’t forget to turn-in.

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Check your understanding

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བཀྲིན་ཆེ།

THANK YOU

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January 2024

PYTHON

Key stage IV

Class X