Python Tutorial

• Python Add PYTHONPATH
• Python Code Blocks and Indentation
• Python Comment
• Python Variable
• Python Data Type
• Python Type Conversion and Casting
• Python Input and Output
• Python Operator
• Python Iterator
• Python Generator

Python Flow Control

• Python if else
• Python for Loops
• Python while Loops
• Python break Statement
• Python continue Statement
• Python pass Statement
• Python switch Statement

Python Functions

• Python Function
• Python Recursion
• Python Anonymous/Lambda Function
• Python Modules
• Python Package

Python Data Types

• Python Number
• Python String
• Python List
• Python Tuple
• Python Set
• Python Dictionary

Python Date and Time

• Python datetime
• strftime(): from datetime to readable string
• strptime(): read string to datetime
• Get current date and time
• Make a time delay
• Convert between local time and UTC time
• Get whole program execution time
• Iterate through a range of dates
• Get the last day of month
• Add/subtract a day
• Convert seconds to HH:MM:SS

Python Files

• Python Open and Close File
• Python Read File
• Python Write File
• Python Move File
• Python Remove File and Directory
• Read Write CSV file
• Read Write JSON file
• Zip File and Directory
• List all files of a directory
• List all sub-directories of directory
• Check a file or directory exists
• Create a directory safely
• Get current directory and file path
• Read big file
• Web page and file download over HTTP
• Search and replace a line to file
• Get file modification time
• Read specific lines from a file by line number
• Check file size
• Get filename and extension

Python String

• String updating, replacing and deleting
• Formatting of Strings
• String format converting
• Convert ASCII string
• String Escape Sequencing
• String lower and upper case
• Find substring in a string
• Count all occurrences of a substring
• Compare two strings
• Split a string into a list
• Split strings into words with multiple delimiters
• Extract numbers from a string
• Conbine items in a list to a single string
• Put a int variable inseide a string
• Compare string in case insensitive
• Check if multiple strings exist in another string
• Check if string exists in a list of strings
• Generate random string
• Remove trailing whitespace in strings

Python List

• List items Adding
• List items Accessing
• List items removing
• List items modifying
• List items iterating
• List items sorting
• List Comprehension
• Convert string representation of list to a list
• Clone a list
• Rotate a list
• Remove duplicates from list
• Define a two-dimensional array
• Sort a list of lists by value
• Sort list based on values from another list
• Sort a list of objects by an attribute of the objects
• Split a list into evenly sized chunks
• Creare a flat list out of a nested list
• Get all possible combinations of a list's elements
• Get the Cartesian product of a series of lists
• Find the index of an element in a list
• Concatenate two list
• Count the occurrences of a list item
• Transpose list of lists
• Find the difference between two lists
• Select items from list randomly
• Iterate a list as (current, next) pair
• Shuffle a list
• Find the cumulative sum of numbers in a list
• Get unique values from a list
• Generate all permutations of a list
• Find the intersection between two lists
• Find the duplicates in a list
• Check item in list
• Convert a list to a string
• Find the average of a list
• Alternate combine two lists
• Extract specific element from each sublist

Python Dictionary

• Add and Modify Dictionary elements
• Delete elements from Dictionary
• Sort dictionary by key
• Sort dictionary by value
• Combine and merge dictionaries
• Convert a String representation of a Dictionary to a dictionary
• Get key by value in dictionary
• Copy a dictionary and edit the copy only
• Create dictionary with dict comprehension and iterables
• Get key with maximum value in dictionary
• Make dictionary from list
• Filter dictionary to contain specific keys

Python Variable

• Python Global Variables and Global Keyword
• Python Local and Nonlocal Variables
• Python Static Class variables
• Create variable variables
• Create variables dynamically in while loop
• Test Single Variable in Multiple Values
• Swap two variables
• Set a Python variable to 'undefined'
• Set and access environment variables

Python Input/Output

• Formatting Output
• Interactive Input/Output
• Indefinitely Request User Input Until a Valid Response
• Read user input as number
• Pretty print JSON
• Print number

Python Exceptions

• Python Exception and Error
• Python AssertionError
• Python AttributeError
• Python EOFError
• Python FloatingPointError
• Python GeneratorExit
• Python ImportError and ModuleNotFoundError
• Python IndexError
• Python KeyError
• Python MemoryError
• Python NameError
• Python OverflowError
• Python TypeError

Python Advanced

• Access the index in for loops
• Change index of a for loop
• ** operator in a function call
• * operator in a function call
• Sort a list of tuples by value
• Transpose list of tuples
• Calculate Euclidean distance btween two points
• Resize an image and keep its aspect ratio
• Check number
• Generate random integers

How to select items from list randomly in Python

In Python, you can use the random module to select items from a list randomly. Here are a few common ways to do this:

• Select a single item randomly using random.choice():

import random

my_list = [1, 2, 3, 4, 5]
random_item = random.choice(my_list)
print(random_item)

• Select multiple unique items randomly using random.sample():

import random

my_list = [1, 2, 3, 4, 5]
num_items = 3
random_items = random.sample(my_list, num_items)
print(random_items)

Note that random.sample() raises a ValueError if the specified sample size is larger than the size of the input list.

• Shuffle the list randomly using random.shuffle():

import random

my_list = [1, 2, 3, 4, 5]
random.shuffle(my_list)
print(my_list)

After shuffling the list, you can take the first n items, for example, as your random selection. Note that this method modifies the input list in place. If you want to keep the original list unchanged, make a copy before shuffling.

import random

my_list = [1, 2, 3, 4, 5]
shuffled_list = my_list.copy()
random.shuffle(shuffled_list)

num_items = 3
random_items = shuffled_list[:num_items]
print(random_items)

Choose the method that best suits your needs depending on whether you need a single random item, multiple unique random items, or a shuffled list.

1. Randomly pick element from list in Python:

   • Description: Randomly picking a single element from a list.
   • Code:

     import random
     
     my_list = [1, 2, 3, 4, 5]
     random_element = random.choice(my_list)
     print("Randomly Picked Element:", random_element)
     

2. Choose random items from list Python:

   • Description: Choosing a specified number of random items from a list.
   • Code:

     import random
     
     my_list = [1, 2, 3, 4, 5]
     num_items = 3
     random_items = random.sample(my_list, num_items)
     print("Randomly Chosen Items:", random_items)
     

3. Random sampling from list in Python:

   • Description: Performing random sampling from a list.
   • Code:

     import random
     
     my_list = [1, 2, 3, 4, 5]
     sample_size = 2
     random_sample = random.sample(my_list, sample_size)
     print("Random Sample:", random_sample)
     

4. Python random choice from list:

   • Description: Making a random choice from a list.
   • Code:

     import random
     
     my_list = ['apple', 'orange', 'banana', 'grape']
     random_fruit = random.choice(my_list)
     print("Randomly Chosen Fruit:", random_fruit)
     

5. Shuffle and select random element from list in Python:

   • Description: Shuffling a list and selecting a random element.
   • Code:

     import random
     
     my_list = [1, 2, 3, 4, 5]
     random.shuffle(my_list)
     random_element = my_list[0]
     print("Shuffled List:", my_list)
     print("Randomly Selected Element:", random_element)
     

6. Randomly select multiple items from list Python:

   • Description: Randomly selecting multiple items from a list.
   • Code:

     import random
     
     my_list = ['a', 'b', 'c', 'd', 'e']
     num_items = 3
     random_selection = random.sample(my_list, num_items)
     print("Randomly Selected Items:", random_selection)
     

7. Select n random elements from list in Python:

   • Description: Selecting a specified number of random elements from a list.
   • Code:

     import random
     
     my_list = [10, 20, 30, 40, 50]
     num_elements = 2
     random_elements = random.sample(my_list, num_elements)
     print("Randomly Selected Elements:", random_elements)
     

8. Python random sampling without replacement from list:

   • Description: Performing random sampling without replacement from a list.
   • Code:

     import random
     
     my_list = ['red', 'green', 'blue', 'yellow']
     sample_size = 2
     random_sample = random.choices(my_list, k=sample_size)
     print("Random Sample without Replacement:", random_sample)
     

9. How to randomly pick elements with probability from list in Python:

   • Description: Randomly picking elements from a list with specified probabilities.
   • Code:

     import random
     
     my_list = ['apple', 'orange', 'banana', 'grape']
     probabilities = [0.3, 0.2, 0.1, 0.4]
     random_fruit = random.choices(my_list, weights=probabilities, k=1)[0]
     print("Randomly Chosen Fruit with Probability:", random_fruit)