Print Function

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What is print() in Python?

The print() function in Python is used to display output to the console.

print("Hello, World!")

Output:

Hello, World!

Syntax of print()

print(*objects, sep=' ', end='\n', file=sys.stdout, flush=False)

Parameter	Description
*objects	One or more values to print
sep	Separator between values (default is space ' ')
end	What to print at the end (default is newline '\n')
file	Where to send the output (default is screen/console)
flush	Whether to forcibly flush the stream

Step-by-Step: Practical Examples

1. Basic String Output

print("Machine Learning is awesome!")

Output:

Machine Learning is awesome!

2. Printing Variables

model = "RandomForest"
accuracy = 94.5

print("Model:", model)
print("Accuracy:", accuracy)

Output:

Model: RandomForest
Accuracy: 94.5

Practical Tip for ML: Use this to report intermediate results like accuracy, loss, epoch number, etc.

3. Using sep for Formatting

print("Accuracy", 94.5, "percent", sep=" - ")

Output:

Accuracy - 94.5 - percent

Tip: Use sep when printing multiple ML metrics in one line.

4. Using end to Stay on Same Line

for i in range(3):
    print(i, end=", ")

Output:

0, 1, 2, 

Tip: Useful for printing progress, epochs, or loops in ML.

5. Print Multiple Data Types

loss = 0.2456
print("Loss value:", loss, "| Type:", type(loss))

Output:

Loss value: 0.2456 | Type: <class 'float'>

Tip: Always confirm data types when preprocessing data in ML.

6. f-Strings for Clean ML Logging (Python 3.6+)

epoch = 5
acc = 87.23
loss = 0.123

print(f"Epoch: {epoch}, Accuracy: {acc:.2f}%, Loss: {loss:.4f}")

Output:

Epoch: 5, Accuracy: 87.23%, Loss: 0.1230

Tip: f-strings are the most common and readable way to log training progress.

7. Redirecting Output to a File

with open("log.txt", "w") as f:
    print("Training started...", file=f)

Tip: Use this in ML to save logs, especially when training on remote servers.

8. Using flush=True for Real-Time Output

import time

for i in range(3):
    print(f"Training step {i}", end='\r', flush=True)
    time.sleep(1)

Tip: Helpful when printing training progress bars or live metrics in the console.

Summary

Concept	Example
Basic Print	print("Hello")
Variables	print("Accuracy:", acc)
sep	print("a", "b", sep="-")
end	print(i, end=" ")
f-String	print(f"Loss: {loss:.4f}")
To File	print("log", file=f)
Real-time	print(".", end="", flush=True)

Keywords

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