Hello World

A sample Python program is shown here.

def greet(name):
    return f"Hello, {name}!"

if __name__ == "__main__":
    message = greet("world")
    print(message)

Run the program as below:

$ python hello.py
Strings
str_single = "Hello"
str_multiline = """Multiline
string"""
print(str_multiline.upper())

Useful string methods:

name = "John Doe"
print(name.lower())  # john doe
print(name.split())  # ['John', 'Doe']
Numbers
integer = 42
floating_point = 3.14
complex_number = 2 + 3j

# Converting between types
float_to_int = int(3.7)  # 3

Working with NumPy for advanced number manipulation:

import numpy as np
array = np.array([1, 2, 3])
print(array.mean())  # 2.0
Condition
day = "sunday"

if day in ["sunday", "saturday"]:
    print("Rest!")
elif day == "monday" and is_tired():
    print("Groan!")
else:
    print("Work!")

Example with try/except:

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")
finally:
    print("Cleanup complete.")
Loops

For loop example:

for i in range(5):
    print(f"Iteration {i}")

While loop example:

count = 0
while count < 5:
    print(f"Count is {count}")
    count += 1
File Operations

Reading and writing text files:

with open("example.txt", "w") as file:
    file.write("Hello, File!")

with open("example.txt", "r") as file:
    content = file.read()
    print(content)

Handling CSV files with pandas:

import pandas as pd

# Reading a CSV file
data = pd.read_csv("data.csv")
print(data.head())

# Writing a CSV file
data.to_csv("output.csv", index=False)