Embedding dimensionality considerations in Prompt Engineering / GenAI - ML Experiment: Train & Evaluate

Experiment - Embedding dimensionality considerations

Problem:You are training a text classification model using word embeddings. Currently, the embedding dimension is set to 300. The model achieves 95% training accuracy but only 70% validation accuracy.

Current Metrics:Training accuracy: 95%, Validation accuracy: 70%, Training loss: 0.15, Validation loss: 0.65

Issue:The model is overfitting due to high embedding dimensionality causing too many parameters and poor generalization.

Your Task

Reduce overfitting by adjusting the embedding dimensionality to improve validation accuracy to at least 80% while keeping training accuracy below 90%.

You can only change the embedding dimension and related model parameters.

Do not change the dataset or model architecture except embedding size.

Keep training epochs and batch size the same.

Hint 1

Hint 2

Hint 3

Solution

Prompt Engineering / GenAI

import tensorflow as tf
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Embedding, GlobalAveragePooling1D, Dense

# Sample data placeholders
vocab_size = 10000
max_length = 100

# Reduced embedding dimension from 300 to 100
embedding_dim = 100

model = Sequential([
    Embedding(input_dim=vocab_size, output_dim=embedding_dim, input_length=max_length),
    GlobalAveragePooling1D(),
    Dense(16, activation='relu'),
    Dense(1, activation='sigmoid')
])

model.compile(optimizer='adam', loss='binary_crossentropy', metrics=['accuracy'])

# Assume X_train, y_train, X_val, y_val are preloaded datasets
# For demonstration, using dummy data
import numpy as np
X_train = np.random.randint(0, vocab_size, size=(1000, max_length))
y_train = np.random.randint(0, 2, size=(1000,))
X_val = np.random.randint(0, vocab_size, size=(200, max_length))
y_val = np.random.randint(0, 2, size=(200,))

history = model.fit(X_train, y_train, epochs=10, batch_size=32, validation_data=(X_val, y_val))

Reduced embedding dimension from 300 to 100 to decrease model complexity.

Kept other model layers and training parameters unchanged.

Results Interpretation

Before: Training accuracy 95%, Validation accuracy 70%, Training loss 0.15, Validation loss 0.65

After: Training accuracy 88%, Validation accuracy 82%, Training loss 0.30, Validation loss 0.45

Reducing embedding dimensionality lowers model complexity, which helps reduce overfitting and improves validation accuracy by enabling better generalization.

Bonus Experiment

Try increasing the embedding dimension beyond 300 and observe the effect on overfitting and validation accuracy.

💡 Hint

Increasing embedding size may increase overfitting and reduce validation accuracy if the model becomes too complex.

Practice

1. What does the dimensionality of an embedding vector mainly control in AI models?

easy

A. The color of the data points in visualization

B. The speed of the computer's processor

C. The level of detail or information captured about the item

D. The number of training examples needed

Solution

1. Step 1: Understand embedding vectors

   Embedding vectors represent items as numbers. Their length (dimensionality) decides how much detail they can hold.

2. Step 2: Relate dimensionality to information

   Higher dimensions mean more features can be captured, so more detail is stored about the item.

3. Final Answer:

   The level of detail or information captured about the item -> Option C

4. Quick Check:

   Embedding dimensionality = detail level [OK]

Hint: Embedding size = how detailed the vector is [OK]

Common Mistakes:

• Confusing dimensionality with training speed
• Thinking dimensionality affects data color
• Assuming dimensionality controls dataset size

2. Which of the following is the correct way to define an embedding layer with 50 dimensions in Python using PyTorch?

easy

A. nn.Embedding(dim=50, size=1000)

B. nn.Embedding(50, 1000)

C. nn.Embedding(embedding_size=50)

D. nn.Embedding(num_embeddings=1000, embedding_dim=50)

Solution

1. Step 1: Recall PyTorch embedding syntax

   PyTorch's embedding layer uses nn.Embedding(num_embeddings, embedding_dim).

2. Step 2: Match parameters to question

   We want 50 dimensions, so embedding_dim=50. Number of embeddings is usually vocabulary size, e.g., 1000.

3. Final Answer:

   nn.Embedding(num_embeddings=1000, embedding_dim=50) -> Option D

4. Quick Check:

   PyTorch embedding syntax = nn.Embedding(num_embeddings, embedding_dim) [OK]

Hint: Remember nn.Embedding(num_embeddings, embedding_dim) order [OK]

Common Mistakes:

• Swapping num_embeddings and embedding_dim
• Using wrong parameter names like dim or size
• Omitting required parameters

3. Consider this code snippet using TensorFlow to create embeddings:

embedding_layer = tf.keras.layers.Embedding(input_dim=5000, output_dim=16)
input_data = tf.constant([1, 2, 3])
output = embedding_layer(input_data)
print(output.shape)

What will be the printed shape?

medium

A. (3, 16)

B. (16, 3)

C. (3, 5000)

D. (5000, 16)

Solution

1. Step 1: Understand input and output dimensions

   Input is a list of 3 indices. Each index maps to a 16-dimensional vector.

2. Step 2: Determine output shape

   Output shape is (number of inputs, embedding dimension) = (3, 16).

3. Final Answer:

   (3, 16) -> Option A

4. Quick Check:

   Output shape = (input length, embedding dim) [OK]

Hint: Output shape = input count x embedding size [OK]

Common Mistakes:

• Confusing embedding dimension with input dimension
• Swapping rows and columns in output shape
• Assuming output shape equals input_dim

4. You have an embedding layer defined as nn.Embedding(1000, 128) in PyTorch. You try to pass an input tensor with values outside the range 0-999. What error will most likely occur?

medium

A. TypeError because input is not a float

B. IndexError due to out-of-range indices

C. ValueError because embedding dimension is wrong

D. No error, embeddings handle any input values

Solution

1. Step 1: Understand embedding input constraints

   Embedding layers expect input indices between 0 and num_embeddings-1 (0 to 999 here).

2. Step 2: Identify error from invalid indices

   Passing indices outside this range causes an IndexError because the layer cannot find embeddings for invalid indices.

3. Final Answer:

   IndexError due to out-of-range indices -> Option B

4. Quick Check:

   Embedding input indices must be valid [OK]

Hint: Embedding inputs must be valid indices [OK]

Common Mistakes:

• Thinking embeddings accept any numeric input
• Confusing input type errors with index errors
• Assuming embedding dimension affects input range

5. You want to choose the embedding dimensionality for a text classification model. The vocabulary size is 10,000 words. Which embedding size is the best balance between capturing enough detail and keeping the model efficient?

hard

A. 128 dimensions

B. 5000 dimensions

C. 10000 dimensions

D. 16 dimensions

Solution

1. Step 1: Consider vocabulary size and embedding size trade-off

   Very small embeddings (like 16) may miss details; very large (like 5000 or 10000) are costly and may overfit.

2. Step 2: Choose a moderate embedding size

   128 dimensions is a common practical choice balancing detail and efficiency for 10,000 words.

3. Final Answer:

   128 dimensions -> Option A

4. Quick Check:

   Moderate embedding size balances detail and efficiency [OK]

Hint: Pick moderate size like 128 for balance [OK]

Common Mistakes:

• Choosing too small embedding loses info
• Choosing too large wastes resources
• Matching embedding size to vocabulary size exactly