Deep Learning Libraries

machine-learning-ai
Understand tensors and where PyTorch and TensorFlow/Keras fit.
  • Level: Beginner to intermediate
  • Estimated time: 35–50 minutes
  • You will learn: Understand tensors and where PyTorch and TensorFlow/Keras fit.
  • Practice in: Jupyter or Google Colab

Questions

  • What problem does Deep Learning Libraries help us solve in a small Python program?
  • What should we predict before running the example?
  • What value, output, or error should we inspect after changing one line?

Objectives

  • Run a complete example for deep-learning libraries in Colab.
  • Explain the example line by line using plain language.
  • Change one part of the code and predict the result before running it.
  • Recognize one common mistake and use the error message as evidence.

Hands-on episode: Deep Learning Libraries

A tensor is a multi-dimensional numerical array. Deep-learning libraries such as PyTorch and TensorFlow/Keras organize tensors, model layers, training loops, and automatic differentiation.

We will learn this by running code, not by memorizing a definition first. Open the Colab notebook from the button above, find this section, and run each cell in order. Keep a small note beside the notebook with three columns: prediction, actual result, and what changed.

Example 1.1

Predict the meaning of each dimension in this batch shape.

import torch

batch = torch.zeros((4, 3))
print(batch.shape)

Run the cell once without editing it. If the result is different from your prediction, leave the prediction visible and write one sentence about the difference. That sentence is more useful than a perfect first guess.

Explain Example 1.1

  • The tensor contains zeros, which makes the values unimportant for this shape lesson.
  • The first dimension, 4, can represent four examples in a batch.
  • The second dimension, 3, can represent three features per example.

Now explain the example out loud or in a Markdown cell. Use short sentences: “this line creates…”, “this name stores…”, “this output appears because…”. If you cannot explain a line yet, run only the lines above it and inspect the values that exist at that moment.

Challenge 1.1

NoteChallenge

Change the shape to (4, 3, 2) and write a possible interpretation. For images or text, extra dimensions carry structured information.

Show a safe way to approach the challenge
  1. Copy Example 1.1 into a new Colab cell.
  2. Change exactly one value, name, condition, or line.
  3. Write the expected output before running the cell.
  4. Run the cell and compare the actual result with your prediction.
  5. If the result surprises you, undo the change and try a smaller one.

Suggested first move: Change the shape to (4, 3, 2) and write a possible interpretation.

Debugging checkpoint 1.1

WarningDebugging checkpoint

Do not start with deep learning just because it sounds powerful. First build a simple baseline, inspect the data, and understand the task. Many poor models fail because of data quality or evaluation, not because the neural network was not fancy enough.

Do not debug by rewriting the whole example. Read the error type or surprising output, inspect the closest value with print(...) or type(...), then change one thing. This is the same routine you will use in larger projects.

Apply it

Create a small tensor, print its shape, add a second tensor of the same shape, and explain what each dimension represents in plain language.

Finish by adding a Markdown cell that answers: What did this example teach me that I can reuse in a project?

Key points

  • Learn the concept by running a complete, small example first.
  • Predict before execution so your thinking becomes visible.
  • Change one thing at a time so cause and effect stay clear.
  • Treat errors as clues about the exact line or value Python could not handle.

Why this matters

Understand tensors and where PyTorch and TensorFlow/Keras fit.

This lesson combines related subtopics that belong together in one learning conversation. You will still pause for a quiz after each section, but you do not need to jump between separate pages while building one clear explanation.

NoteGuiding questions

By the end of this lesson, you should be able to answer:

  • How do the sections in Deep Learning Libraries fit together?
  • Which small example demonstrates each section?
  • Which debugging clue should I check first for each section?
NoteLearning objectives

You will practice how to:

  • explain the shared concept for this lesson;
  • use each section as one step in a larger workflow;
  • complete 3 short section quizzes before moving on;
  • connect examples, mistakes, and debugging routines.

Lesson map

  • 1. Tensors — Understand tensors as multi-dimensional numerical arrays used in deep learning.
  • 2. PyTorch Overview — Understand where PyTorch fits for tensors, neural networks, and research workflows.
  • 3. TensorFlow and Keras Overview — Understand TensorFlow/Keras as tools for building and training neural networks.

1. Tensors

Understand tensors as multi-dimensional numerical arrays used in deep learning.

TipAnalogy

A tensor is a stack of grids: one number, a row, a table, or a cube of numbers depending on dimensions.

What this means

A tensor generalizes scalars, vectors, and matrices to more dimensions.

Example 1

Predict what will happen before you run the code.

import numpy as np

image_batch = np.zeros((10, 28, 28))
print(image_batch.shape)

Step-by-step explanation

  1. import numpy as np — pause here and say what this line reads, creates, changes, or displays.
  2. image_batch = np.zeros((10, 28, 28)) — pause here and say what this line reads, creates, changes, or displays.
  3. print(image_batch.shape) — pause here and say what this line reads, creates, changes, or displays.

After running the example, compare the actual output with your prediction. If they differ, do not erase your prediction. The difference is the part that can teach you the most.

Challenge

NotePractice

Change one input value, predict the new output, run the code, and explain the difference in one sentence.

Show one possible solution path
  1. Copy Example 1 into Colab, Jupyter, or a .py file.
  2. Mark the line you plan to change.
  3. Write a one-sentence prediction.
  4. Run the changed code.
  5. If the result surprises you, restore the original and change a smaller part.

The goal is not to find the only correct answer. The goal is to create a small experiment where you can explain cause and effect.

Common mistakes

WarningCommon mistake

Most tensor bugs are shape bugs. Print shapes before changing model code.

When you get stuck, use this debugging routine:

  1. Read the last line of the error message or inspect the unexpected output.
  2. Find the smallest line of code that could be responsible.
  3. Print or inspect the value and type at that point.
  4. Change one thing.
  5. Run again and record what changed.

Check your understanding

This quiz checks the ideas in this section before you move on.

2. PyTorch Overview

Understand where PyTorch fits for tensors, neural networks, and research workflows.

TipAnalogy

PyTorch is a workshop for building trainable machines from tensor parts.

What this means

PyTorch provides tensor computation and automatic differentiation for deep learning.

Example 2

Predict what will happen before you run the code.

import torch

x = torch.tensor([1.0, 2.0, 3.0])
print(x * 2)

Step-by-step explanation

  1. import torch — pause here and say what this line reads, creates, changes, or displays.
  2. x = torch.tensor([1.0, 2.0, 3.0]) — pause here and say what this line reads, creates, changes, or displays.
  3. print(x * 2) — pause here and say what this line reads, creates, changes, or displays.

After running the example, compare the actual output with your prediction. If they differ, do not erase your prediction. The difference is the part that can teach you the most.

Challenge

NotePractice

Change one input value, predict the new output, run the code, and explain the difference in one sentence.

Show one possible solution path
  1. Copy Example 1 into Colab, Jupyter, or a .py file.
  2. Mark the line you plan to change.
  3. Write a one-sentence prediction.
  4. Run the changed code.
  5. If the result surprises you, restore the original and change a smaller part.

The goal is not to find the only correct answer. The goal is to create a small experiment where you can explain cause and effect.

Common mistakes

WarningCommon mistake

PyTorch tensors track devices and gradients. Device or shape mismatches are common first errors.

When you get stuck, use this debugging routine:

  1. Read the last line of the error message or inspect the unexpected output.
  2. Find the smallest line of code that could be responsible.
  3. Print or inspect the value and type at that point.
  4. Change one thing.
  5. Run again and record what changed.

Check your understanding

This quiz checks the ideas in this section before you move on.

3. TensorFlow and Keras Overview

Understand TensorFlow/Keras as tools for building and training neural networks.

TipAnalogy

Keras is like modular building blocks for neural networks: stack layers, choose training rules, fit data.

What this means

Keras provides a high-level model-building interface on top of TensorFlow.

Example 3

Predict what will happen before you run the code.

import tensorflow as tf

model = tf.keras.Sequential([tf.keras.layers.Dense(1)])
print(model)

Step-by-step explanation

  1. import tensorflow as tf — pause here and say what this line reads, creates, changes, or displays.
  2. model = tf.keras.Sequential([tf.keras.layers.Dense(1)]) — pause here and say what this line reads, creates, changes, or displays.
  3. print(model) — pause here and say what this line reads, creates, changes, or displays.

After running the example, compare the actual output with your prediction. If they differ, do not erase your prediction. The difference is the part that can teach you the most.

Challenge

NotePractice

Change one input value, predict the new output, run the code, and explain the difference in one sentence.

Show one possible solution path
  1. Copy Example 1 into Colab, Jupyter, or a .py file.
  2. Mark the line you plan to change.
  3. Write a one-sentence prediction.
  4. Run the changed code.
  5. If the result surprises you, restore the original and change a smaller part.

The goal is not to find the only correct answer. The goal is to create a small experiment where you can explain cause and effect.

Common mistakes

WarningCommon mistake

Deep learning libraries can install heavy dependencies. Use Colab when local setup becomes a distraction.

When you get stuck, use this debugging routine:

  1. Read the last line of the error message or inspect the unexpected output.
  2. Find the smallest line of code that could be responsible.
  3. Print or inspect the value and type at that point.
  4. Change one thing.
  5. Run again and record what changed.

Check your understanding

This quiz checks the ideas in this section before you move on.

Notebook and Colab practice

Open a blank notebook at https://colab.new. Use one section at a time: copy the Example 1, predict the result, run it, answer the section quiz, and then move to the next section. This is better than copying the entire page at once.

Instructor note

Teaching notes
  • Treat each section as a short teaching episode.
  • Pause for the section quiz before introducing the next section.
  • Ask learners to compare sections: what stayed the same, and what changed?
  • If time is short, teach the first two sections live and assign the rest as practice.

Key points

TipKey points
  • Tensors: A tensor generalizes scalars, vectors, and matrices to more dimensions.
  • PyTorch Overview: PyTorch provides tensor computation and automatic differentiation for deep learning.
  • TensorFlow and Keras Overview: Keras provides a high-level model-building interface on top of TensorFlow.
  • Use the section quizzes as gates: review before moving on if a quiz feels uncertain.

References

  • scikit-learn documentation: https://scikit-learn.org/stable/
  • PyTorch documentation: https://pytorch.org/docs/stable/index.html
  • TensorFlow documentation: https://www.tensorflow.org/api_docs
  • Hugging Face Transformers documentation: https://huggingface.co/docs/transformers/
  • Python Tutorial: https://docs.python.org/3/tutorial/
  • Quarto OJS documentation: https://quarto.org/docs/interactive/ojs/
  • ipywidgets documentation: https://ipywidgets.readthedocs.io/en/stable/
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