Python For Beginners
What is Python?
Python is a high-level, general-purpose programming language. It is known for its simplicity and readability. Python is ideal for beginners and widely used in various fields like web development, data science, and automation.
What is Python Coding?
Interpreter
An interpreter is a program that translates a programming language into a comprehensible language. It converts high-level language to an intermediate language and contains pre-compiled code, source code, etc.
In Python, the Python interpreter reads Python code, interprets it, and executes it line by line.
Comments
Comments are lines in a program ignored by the interpreter or compiler. They do not affect the execution of the code and are used to add explanations, notes, or reminders.
Types of comments in Python:
- Single-line comments: Start with
#. - Multi-line comments: Enclosed in triple quotes (
'''or""").
Variables
Variables in Python are used to store data that can be used and manipulated by the program. Python is dynamically typed, so you don’t need to specify the type of a variable.
Keywords
Keywords in Python are reserved words with special meanings. They cannot be used as variable names, function names, or any other identifiers. Examples include if, else, while, for, import, def, and return.
Input and Print
- Input: The
input()function allows users to input data during program execution. - Print: The
print()function outputs data to the monitor.
Example:
a = input('Enter your name: ')
print(a)
# Output:
# Enter your name: Jeff
# Jeff
Data Types
Python supports various data types:
- Numeric types:
int,float,complex - Text type:
str - Boolean type:
bool - Sequence types:
list,tuple,range - Mapping type:
dict - Set types:
set,frozenset - Binary types:
bytes,bytearray,memoryview - None type:
None
Numbers
Examples:
x = 5 # int
y = 4.9 # float
z = 5 + 5j # complex
Strings
Strings are sequences of characters enclosed in quotes.
Examples:
string = 'Hello, World!'
print(string[0:5]) # Slicing: Output -> Hello
Boolean
Boolean values represent True or False.
Examples:
p = 10
q = 5
print(p > q) # Output: True
Lists
A list is a built-in data structure used to store an ordered collection of items.
Creating a List
my_list = [1, 2, 3, 4, 5]
mixed_list = [1, "hello", 3.14, True]
Accessing Elements
print(my_list[0]) # Output: 1
print(mixed_list[1]) # Output: hello
print(my_list[-1]) # Output: 5
Slicing
subset = my_list[1:4] # Elements from index 1 to 3
print(subset) # Output: [2, 3, 4]
Modifying a List
my_list[2] = 10
print(my_list) # Output: [1, 2, 10, 4, 5]
Common Methods
my_list.append(6) # Adds an element to the end
my_list.remove(4) # Removes the first occurrence of a value
my_list.insert(2, "new") # Inserts an element at a specific index
print(my_list) # Output: [1, 2, 'new', 10, 5, 6]
Tuples
A tuple is an immutable, ordered collection of items.
Creating a Tuple
my_tuple = (1, 2, 3)
single_item_tuple = (1,) # A comma is required for single-item tuples
Accessing Elements
print(my_tuple[0]) # Output: 1
Unpacking Tuples
coordinates = (10, 20)
x, y = coordinates
print(x, y) # Output: 10 20
Dictionaries
A dictionary stores a collection of key-value pairs.
Creating a Dictionary
my_dict = {"key1": "value1", "key2": "value2", "key3": "value3"}
Accessing Values
print(my_dict["key1"]) # Output: value1
Modifying a Dictionary
my_dict["key2"] = 42 # Update value
my_dict["new_key"] = 99 # Add new key-value pair
del my_dict["key3"] # Delete a key-value pair
print(my_dict) # Output: {'key1': 'value1', 'key2': 42, 'new_key': 99}
Common Methods
for key, value in my_dict.items():
print(f"{key}: {value}")
Operators
Arithmetic Operators
- Addition:
+ - Subtraction:
- - Multiplication:
* - Division:
/ - Modulus:
% - Exponentiation:
** - Floor Division:
//
Comparison Operators
- Greater than:
> - Less than:
< - Greater than or equal to:
>= - Less than or equal to:
<=
Conditional Statements
Control the flow of execution with if, elif, and else.
Example:
x = 3
if x == 2:
print("x is 2")
elif x == 3:
print("x is 3")
else:
print("x is not 2 nor 3")
Loops
For Loop
Iterates over a sequence.
Syntax:
for var in sequence:
# Code to execute
While Loop
Continues until a condition becomes False.
Syntax:
while condition:
# Code to execute
Functions
Functions are blocks of reusable code.
Example:
def hello():
print("Welcome to ORIGO")
return 1
Modules
A module is a Python file containing functions and variables.
Examples:
mathre(Regex)datetimerandom
Libraries
Python libraries are collections of modules.
Examples:
numpymatplotlibopencv-python
Packages
A package is a directory of modules, including a special __init__.py file.
Examples:
numpypandas