Python Basics - Data Structures - Module 2

 In this module 2, we divide in three parts: Parts 1 (List and Tuples), part 2 (Dictionaries) and part 3 (Sets)

Image 1 - Pad Thai, fried noodle.

Parts 1 (List and Tuples)

Tuples is data type that built in Python to store multiple items in a single variable.

Tuples are similar to List, tey are immutable or their values can't be changed.

Tuples are an ordered sequence:

Ratings =(10,9,6,4,2)

Tuples:

String: 'disco'

int: 10

float: 1.2

tuple1 =('disco',10,1.2)

type(tuple1)=tuple

tuple1 =('disco',10,1.2)

index:       0        1    2

hence, tuple1[0]:'disco'

tupl1[1]:10

Index can be negative too:

tuple1 =('disco',10,1.2)

index:       -3      -2  -1

hence, tuple1[-3]:'disco'

tupl1[-1]:1.2

We can add tuples:

tuple1 =('disco',10,1.2)

tuple2 = tuple1 +("hard".10)

tuple2=('disco',10,1.2,"hard",10) 

index =     0       1   2       3      4

tuple2=('disco',10,1.2,"hard",10) 

index =     0       1   2      3       4

tuple2[0:3]: ('disco',10,1.2)

tuple2[3]: ('hard', 10)

len command:

len(('disco',10,1.2,"hard",10))= 5

Ratings =(10,9,6,5,10,8,9,6,2)

Ratings1=Ratings

Tuple: Nesting

nested_tuple= ((1, 20, (3, 4), (5, 6))

This nested_tuple contains 3 tuples, each with 2 elements.

We can access the elements of a nested_tuple by using indexing:

print(nested_tuple[1][0])

output: 3 ----> first element of second tuple

List is data type, can contain any data types include integers, strings and objects. Mutable, can be changed.

L=["Michael", 10.1, 1982]

index: 0            1        2

Hence, L[0]: "Michael"

L[1]: 10.1

Negative index:

L=["Michael", 10.1, 1982]

Index:  -3           -2    -1

L[-1]: 1982

L[-3]: "Michael"

List: slicing

L=["Michael", 10.1, 1982, "MJ", 1]

L[3:5]: ["MJ', 1]

Image 2 - Jambu bol, ilustrasi

Practice Quiz: Lists and Tuples

1) Consider the following tuple:

say_what=('say',' what', 'you', 'will')

What is the result of the following say_what[-1] ?

Answer: 'will'

2) Consider the following tuple A=(1,2,3,4,5), 

what is the result of the following:A[1:4]:

answer: (2, 3, 4)

Note: A[1:4] is a slice of the list A that contains elements from index 1 to index 3. The first index is inclusive, while the second index is exclusive.

3) Consider the following tuple A=(1,2,3,4,5). 

What is the result of the following: len(A)

answer: 5

4) Consider the following list B=[1,2,[3,'a'],[4,'b']]. 

What is the result of the following: B[3][1]

answer: b

Note:

B[3] returns the fourth element of the list B, which is [4, 'b'].

B[3][1] returns the second element of the list [4, 'b'], which is 'b'.

Therefore, the result of the expression B[3][1] is 'b'.

5)What is the result of the following operation?

[1,2,3]+[1,1,1]

Answer: [1, 2, 3, 1, 1, 1]

Note: The addition operator corresponds to concatenating a list.

6) What is the length of the list A = [1] after the following operation: A.append([2,3,4,5])

answer: 2

Note: The append() method in Python adds an element to the end of a list. In this case, the list A is initially [1]. After the operation A.append([2,3,4,5]), the new list A will be [1, [2, 3, 4, 5]]. Therefore, the length of the list A after the operation is 2.

7)What is the result of the following: "Hello Mike".split()

Answer: "Hello"," Mike"

Image 3 - Karya seni, Singapura

Part 2 : Dictionaries

List has index and elements

The Dictionary has key and value. 

- keys don't have to be integers. Key usually characters.

- key is immutable and unique

- Values similar to the elements in the List, contains information.

To create Dictionary, we use curly brackets:

{"key1":1, "key2":"2", "key3":[3,3,3], ('key4'):4}

Image 4 - Kemping untuk wisata

Practice Quiz: Dictionary

1) What are the keys of the following dictionary: {"a":1,"b":2}

answer: "a", "b"

2) Consider the following Python Dictionary: Dict={"A":1,"B":"2","C":[3,3,3],"D":(4,4,4),'E':5,'F':6} What is the result of the following operation: Dict["D"]

answer: (4, 4, 4)

 

Image 5 - Semak tidak terurus, ilustrasi

Part 3: Sets

Sets are type of collection means you can input different python types. You place the elements of a set within te curly brackets. 

You notice there are duplicates items.

example:

set1 = {"pop", "rock", "soul", "hard rock", "rock", "R&B", "rock", "disco"}

Convert List to Set:

album_list = [ "Michael Jackson", "Thriller", 1982, "00:42:19", \

              "Pop, Rock, R&B", 46.0, 65, "30-Nov-82", None, 10.0]

album_set = set(album_list) 

The set() function in Python is used to create a set object, which is an unordered collection of unique elements. In the given code snippet, album_list is a list containing 10 elements. When set(album_list) is called, it creates a new set object album_set containing only the unique elements of album_list. The resulting set object will contain the following elements:

{None, 'Pop, Rock, R&B', 1982, 10.0, 46.0, '30-Nov-82', 'Michael Jackson', '00:42:19', 'Thriller', 65}

Image 6 - Buah manggis, masih hijau

Practice Quiz Sets:

1) Consider the following set: {"A","A"}. What will the result be when the set is created?

answer: {"A"}

Note: A set can't have duplicate elements. Therefore the set will only one element which is "A".

2) What is the result of the following: type(set([1,2,3]))

answer: set

note: the result of type(set([1,2,3])) is <class 'set'>

3) What method do you use to add an element to a set?

answer: add

Note: my_set = set()

my_set.add(1)

my_set.add(2)

my_set.add(3)

print(my_set) # Output: {1, 2, 3}

4) What is the result of the following operation: {'a','b'} & {'a'}

answer: {'a'}

Note: The operation {‘a’,‘b’} & {‘a’} is the intersection of two sets. The intersection of two sets is the set of elements that are common to both sets. In this case, the intersection of {‘a’,‘b’} and {‘a’} is the set {‘a’}. Therefore, the result of the operation is {‘a’}.

JJ