Basic Commands in Python 

To begin with, Python provides many basic commands to use data, perform calculations, and input/output manipulations. Finally, we cover so-called Magic Commands: a set of commands mostly used inside Jupyter Notebooks to simplify certain tasks.

Basic Python Commands

1. Printing Output

The print() function is one of the simplest and most used commands in Python. It allows us to display text or data on the screen.

print("Hello, World!")

Output:

Hello, World!

2. Comments

Comments are not executed by Python; they are used to add explanations or notes about the code.

# This is a single-line comment
print("This will run!")  # Inline comment

Output:

This will run!

3. Variables

Variables are placeholders for storing data. You don’t need to declare their type explicitly in Python.

name = "Alice"
age = 25
print("Name:", name)
print("Age:", age)

Output:

Name: Alice
Age: 25

4. Data Types

Python supports multiple data types such as integers, floats, strings, and booleans.

x = 10          # Integer
y = 3.14        # Float
z = "Python"    # String
is_cool = True  # Boolean

print(type(x))  # <class 'int'>
print(type(y))  # <class 'float'>
print(type(z))  # <class 'str'>
print(type(is_cool))  # <class 'bool'>

Output:

<class 'int'>
<class 'float'>
<class 'str'>
<class 'bool'>

5. User Input

The input() function reads data as a string entered by the user.

user_name = input("Enter your name: ")
print("Hello, " + user_name)

Example Interaction:

Enter your name: John
Hello, John

6. Conditional Statements

Control the flow of logic based on conditions using if, elif, and else.

age = 18
if age >= 18:
    print("You are an adult.")
else:
    print("You are a minor.")

Output:

You are an adult.

7. Loops

Loops allow us to repeat a block of code.

For Loop:

for i in range(5):  # Iterates from 0 to 4
    print(i)

Output:

0
1
2
3
4

While Loop:

count = 0
while count < 5:
    print(count)
    count += 1

Output:

0
1
2
3
4

8. Functions

Functions encapsulate reusable logic.

def greet(name):
    return "Hello, " + name

print(greet("Alice"))

Output:

Hello, Alice

9. Lists

Lists are collections of ordered, changeable items.

fruits = ["apple", "banana", "cherry"]
fruits.append("orange")  # Adds an item
print(fruits[0])  # Access the first item
print(fruits)  # Prints the entire list

Output:

apple
['apple', 'banana', 'cherry', 'orange']

Magic Commands in Python (Jupyter Notebook)

Magic commands are specific to Jupyter Notebooks and can greatly improve productivity by handling common tasks efficiently.

1. %pwd

Displays the current working directory.

%pwd

Output:

/path/to/current/directory

2. %ls

Lists files and directories in the current folder.

%ls

Output:

file1.py  file2.txt  notebook.ipynb

3. %time

Measures the execution time of a single line of code.

%time sum(range(1000000))

Output:

CPU times: user 12 ms, sys: 0 ns, total: 12 ms
Wall time: 11 ms
499999500000

4. %%time

Measures the execution time for a block of code.

%%time
total = 0
for i in range(1000000):
    total += i

Output:

CPU times: user 145 ms, sys: 2 ms, total: 147 ms
Wall time: 146 ms

5. %run

Runs a Python script inside the notebook.

%run script.py

Output: (Depends on the content of script.py)

6. %matplotlib

Configures how Matplotlib displays plots.

%matplotlib inline

Output: (Plots will appear inline in the notebook.)

7. %history

Displays a list of previously executed commands.

%history

Output:

1: print("Hello, World!")
2: %pwd
3: sum(range(100))
...

8. %debug

Opens the debugger after an error.

# Example of an error
%debug

Output: (Debugger interface opens for error inspection.)

9. %who

Lists all variables currently defined.

%who

Output:

name   age   fruits

10. %%writefile

Writes content to a file.

%%writefile example.txt
This is a test file written using a magic command.

Output:

Writing example.txt

Advantages of Magic Commands

• Simplify workflow in Jupyter Notebooks.
• Don’t need other tools for frequently needed tasks.
• Integrated debugging and profiling tools.