Tutorial Playlist
200 Lessons1. Introduction to Python
2. Features of Python
3. How to install python in windows
4. How to Install Python on macOS
5. Install Python on Linux
6. Hello World Program in Python
7. Python Variables
8. Global Variable in Python
9. Python Keywords and Identifiers
10. Assert Keyword in Python
11. Comments in Python
12. Escape Sequence in Python
13. Print In Python
14. Python-if-else-statement
15. Python for Loop
16. Nested for loop in Python
17. While Loop in Python
18. Python’s do-while Loop
19. Break in Python
20. Break Pass and Continue Statement in Python
21. Python Try Except
22. Data Types in Python
23. Float in Python
24. String Methods Python
25. List in Python
26. List Methods in Python
27. Tuples in Python
28. Dictionary in Python
29. Set in Python
30. Operators in Python
31. Boolean Operators in Python
32. Arithmetic Operators in Python
33. Assignment Operator in Python
34. Bitwise operators in Python
35. Identity Operator in Python
36. Operator Precedence in Python
37. Functions in Python
38. Lambda and Anonymous Function in Python
39. Range Function in Python
40. len() Function in Python
41. How to Use Lambda Functions in Python?
42. Random Function in Python
43. Python __init__() Function
44. String Split function in Python
45. Round function in Python
46. Find Function in Python
47. How to Call a Function in Python?
48. Python Functions Scope
49. Method Overloading in Python
50. Method Overriding in Python
51. Static Method in Python
52. Python List Index Method
53. Python Modules
54. Math Module in Python
55. Module and Package in Python
56. OS module in Python
57. Python Packages
58. OOPs Concepts in Python
59. Class in Python
60. Abstract Class in Python
61. Object in Python
62. Constructor in Python
63. Inheritance in Python
64. Multiple Inheritance in Python
65. Encapsulation in Python
66. Data Abstraction in Python
67. Opening and closing files in Python
68. How to open JSON file in Python
69. Read CSV Files in Python
70. How to Read a File in Python
71. How to Open a File in Python?
72. Python Write to File
73. JSON Python
74. Python JSON – How to Convert a String to JSON
75. Python JSON Encoding and Decoding
76. Exception Handling in Python
77. Recursion in Python
78. Python Decorators
79. Python Threading
80. Multithreading in Python
81. Multiprocеssing in Python
82. Python Regular Expressions
83. Enumerate() in Python
84. Map in Python
85. Filter in Python
86. Eval in Python
87. Difference Between List, Tuple, Set, and Dictionary in Python
88. List to String in Python
89. Linked List in Python
90. Length of list in Python
91. Reverse a List in Python
92. Python List remove() Method
93. How to Add Elements in a List in Python
94. How to Reverse a List in Python?
95. Difference Between List and Tuple in Python
96. List Slicing in Python
97. Sort in Python
98. Merge Sort in Python
99. Selection Sort in Python
Now Reading
100. Sort Array in Python
101. Sort Dictionary by Value in Python
102. Datetime Python
103. Random Number in Python
104. 2D Array in Python
105. Abs in Python
106. Advantages of Python
107. Anagram Program in Python
108. Append in Python
109. Applications of Python
110. Armstrong Number in Python
111. Assert in Python
112. Binary Search in Python
113. Binary to Decimal in Python
114. Bool in Python
115. Calculator Program in Python
116. chr in Python
117. Control Flow Statements in Python
118. Convert String to Datetime Python
119. Count in python
120. Counter in Python
121. Data Visualization in Python
122. Datetime in Python
123. Extend in Python
124. F-string in Python
125. Fibonacci Series in Python
126. Format in Python
127. GCD of Two Numbers in Python
128. How to Become a Python Developer
129. How to Run Python Program
130. In Which Year Was the Python Language Developed?
131. Indentation in Python
132. Index in Python
133. Interface in Python
134. Is Python Case Sensitive?
135. Isalpha in Python
136. Isinstance() in Python
137. Iterator in Python
138. Join in Python
139. Leap Year Program in Python
140. Lexicographical Order in Python
141. Literals in Python
142. Matplotlib
143. Matrix Multiplication in Python
144. Memory Management in Python
145. Modulus in Python
146. Mutable and Immutable in Python
147. Namespace and Scope in Python
148. OpenCV Python
149. Operator Overloading in Python
150. ord in Python
151. Palindrome in Python
152. Pass in Python
153. Pattern Program in Python
154. Perfect Number in Python
155. Permutation and Combination in Python
156. Prime Number Program in Python
157. Python Arrays
158. Python Automation Projects Ideas
159. Python Frameworks
160. Python Graphical User Interface GUI
161. Python IDE
162. Python input and output
163. Python Installation on Windows
164. Python Object-Oriented Programming
165. Python PIP
166. Python Seaborn
167. Python Slicing
168. type() function in Python
169. Queue in Python
170. Replace in Python
171. Reverse a Number in Python
172. Reverse a string in Python
173. Reverse String in Python
174. Stack in Python
175. scikit-learn
176. Selenium with Python
177. Self in Python
178. Sleep in Python
179. Speech Recognition in Python
180. Split in Python
181. Square Root in Python
182. String Comparison in Python
183. String Formatting in Python
184. String Slicing in Python
185. Strip in Python
186. Subprocess in Python
187. Substring in Python
188. Sum of Digits of a Number in Python
189. Sum of n Natural Numbers in Python
190. Sum of Prime Numbers in Python
191. Switch Case in Python
192. Python Program to Transpose a Matrix
193. Type Casting in Python
194. What are Lists in Python?
195. Ways to Define a Block of Code
196. What is Pygame
197. Why Python is Interpreted Language?
198. XOR in Python
199. Yield in Python
200. Zip in Python
Selection sort in Python is basically an algorithm that sorts out the data in an array in ascending order by finding the minimum element. It does not acquire any extra space and two sub-arrays are maintained in an array for a selection sort in Python without using the function.
Python is a computer programming language used for building web-based applications. In 1991, Guido Van Rossum created it.
Similar to the sorting function in Microsoft Excel, an algorithm called selection sort is used in Python for arranging and sorting out arrays. Two different sub-arrays are maintained for sorting out the elements in an array. The time complexity of the selection sort is about O(N2).
In every iteration, the minimum element from the unsorted array is taken and swapped into the sorted array.
Let us look at the following example to understand the selection sort algorithm better:
Example: Array arr[]= {65, 36, 12, 15, 9}
First Pass
For the first element, wherein 65 is presently stored, after traversing the whole unsorted array, it is found that the minimum element in the block is 9.
Thus replacing 65 with 9. After the first iteration, the number 9, which was the last number in the unsorted array, now, tends to be in the first position.
65 36 12 15 9
Second Pass
For the second position, after traversing the entire array, it is found that the second lowest element is 12.
The second element in the unsorted array is 36 which is now replaced or swapped by the number 12.
9 36 12 15 65
Third Pass
Similarly, for the third position, after traversing the entire array, it is found that the third lowest element is 15.
The third lowest element 15 is placed after the number 12 in the sorted array.
9 12 36 15 65
Fourth Pass
After traversing the array, the fourth-lowest element was found to be 36 and it was placed in the fourth block.
9 12 15 36 65
Last Pass
The number 65, which is the largest number in the array, is automatically sorted.
Finally, you get the sorted array.
Let’s see the implementation of the code
// Function for Selection sort
void selectionSort(int arr[], int n)
{
int i, j, min_idx;
// One by one move boundary of
// unsorted subarray
for (i = 0; i < n - 1; i ) {
// Find the minimum element in
// unsorted array
min_idx = i;
for (j = i 1; j < n; j ) {
if (arr[j] < arr[min_idx])
min_idx = j;
}
// Swap the found minimum element
// with the first element
if (min_idx != i)
swap(arr[min_idx], arr[i]);
}
}
// Function to print an array
void printArray(int arr[], int size)
{
int i;
for (i = 0; i < size; i ) {
cout << arr[i] << " ";
cout << endl;
}
}
// Driver program
int main()
{
int arr[] = {65, 36, 12, 15, 9}
int n = sizeof(arr) / sizeof(arr[0]);
// Function Call
selectionSort(arr, n);
cout << "Sorted array: \n";
printArray(arr, n);
return 0;
}
The code Output:
9,12,15,36,65
Array = [6,7,3,8]
# loop to Traverse through all the elements in the given array
for i in range(len(Array)):
# setting min_indx equal to the first unsorted element
min_indx = i
# Loop to iterate over un-sorted sub-array
for j in range(i 1, len(Array)):
#Finding the minimum element in the unsorted sub-array
if Array[min_indx] > Array[j]:
min_indx = j
# swapping the minimum element with the element at min_index to place it at its correct position
Array[i], Array[min_indx] = Array[min_indx], Array[i]
# Printing the modified array after the selection sort algorithm is applied
print(Array)
The Code Output:
3,6,7,8
Below is an example of the insertion function in Python.
def insertionSort(arr):
n = len(arr) # Get the length of the array
if n <= 1:
return # If the array has 0 or 1 element, it is already sorted, so return
for i in range(1, n): # Iterate over the array starting from the second element
key = arr[i] # Store the current element as the key to be inserted in the right position
j = i-1
while j >= 0 and key < arr[j]: # Move elements greater than key one position ahead
arr[j 1] = arr[j]
j -= 1
arr[j 1] = key
arr = [12, 10, 15, 8, 2]
insertionSort(arr)
print(arr)
The Output:
[2, 8, 10, 12, 15]
Merge sort in Python
The merge sort algorithms as the name indicates divide the input array into two. After sorting out the two halves, the merge sort merges the two into one.
Assuming that arr[l..m] and arr[m 1..r] are sorted, the merge(arr, l, m, r) key operation merges the two sorted subarrays into a single array.
Python uses the same selection sort algorithm to sort out the numbers in ascending order. The article below covers the Python code for the selection sort pseudocode.
The time complexity of the selection sort is about O(N2). It does not require any additional space for performing the selection sort function.Best case scenario - O(N2) - occurs when the array has already been sorted. The array's number of integers, n, is indicated here.The average case (O(N2)) occurs when the array's items are organized in a random manner without regard to any rules.
When the array needs to be organized in ascending order but is now in descending order, the worst scenario is O(N2).
The time complexity of the selection sort remains unchanged irrespective of the input array’s initial order. It is important to find the minimum element in the array to sort it in the ascending order and that is possible only after the entire array is traversed.
At every step, the selection sort algorithm recognizes the minimum element and places it in the right position.
No. of Iterations | Comparisons |
1st | (n-1) |
2nd | (n-2) |
3rd | (n-3) |
……. | …….. |
last | 1 |
The above-given table gives the breakdown of the selection sort time complexity.
The total number of comparisons in the selection sort can be calculated as the sum of (n-1) (n-2) (n-3) …… 1.
This can be attributed to n/(n-1)/2 OR n^2
Thus, the time complexity comes to O(n^2).
One can also analyze the time complexity by looking at the number of loops – that is two nested loops in the selection sort.
This in turn comes to n^2.
The given Python code below provides the selection sort algorithm. The time complexity of the selection sort is about O(n^2).
The entire array is traversed before sorting the array in the ascending order. In every iteration, the minimum element is identified and placed in the correct space. This happens continuously unless the complete array is sorted out in the required ascending manner.
Python Program for Selection Sort:
def selectionSort(array, size):
for ind in range(size):
min_index = ind
for j in range(ind 1, size):
# select the minimum element in every iteration
if array[j] < array[min_index]:
min_index = j
# swapping the elements to sort the array
(array[ind], array[min_index]) = (array[min_index], array[ind])
arr = [2, 45, 0, 15, -14, 99, 55, 64, 747]
size = len(arr)
selectionSort(arr, size)
print('The array after sorting in Ascending Order by selection sort is:')
print(arr)
The Output:
[-14, 0, 2, 15, 45, 55, 64, 99, 747]
The array's elements are sorted using selection sort in ascending order. It is a wonderful method to utilize because it takes up less extra space. It is advantageous to employ because it has an O(n) time complexity.
1. What is Python?
Web-based apps can be created using the computer language Python. It is a robust and user-friendly language that Guido Van Rossum developed and produced; it is also one of the languages of choice for developers and programmers all over the world.
2. What is a selection sort in Python?
Selection sort is an algorithm in Python that is used to sort elements in the array as per the given specifications such as in ascending order.
3. What is an array in Python?
An array is a collection of data stored in contiguous memory locations.
4. Is Python good for beginners?
Yes, Python has been developed with simple codes and syntax. It’s an easy language and programming makes it quite useful for beginners.
5. What is the time complexity of selection sort in Python?
The time complexity of the selection sort in data structure is about O(N2).
6. What is an insertion sort in Python?
Insertion sort in Python is to sort an array. It compares the element besides the key element and then shifts its place to the correct location.
7. What is the difference between insertion sort and selection sort?
The main difference between insertion sort and selection sort is how they sort out the elements in an array. Insertion sorts compares and shifts places of the elements, whereas, selection sort divides the array into two parts – sorted and unsorted. It swaps the elements from unsorted elements to sorted ones.
8. Does upGrad provide courses on Python?
Yes, Python offers courses on Python which covers everything – from basic coding to complex programming on Python.
PAVAN VADAPALLI
Director of Engineering
Director of Engineering @ upGrad. Motivated to leverage technology to solve problems. Seasoned leader for startups and fast moving orgs. Working …Read More
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upGrad does not grant credit; credits are granted, accepted or transferred at the sole discretion of the relevant educational institution offering the diploma or degree. We advise you to enquire further regarding the suitability of this program for your academic, professional requirements and job prospects before enr...