Cosine similarity in NLP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is cosine similarity?

Cosine similarity is a way to measure how similar two things are by looking at the angle between their vectors. It gives a value between -1 and 1, where 1 means exactly the same direction, 0 means no similarity, and -1 means opposite directions.

beginner

How is cosine similarity calculated between two vectors?

Cosine similarity is calculated by dividing the dot product of two vectors by the product of their lengths (magnitudes). Formula: cosine_similarity = (A · B) / (||A|| * ||B||).

beginner

Why is cosine similarity useful in text analysis?

Cosine similarity helps compare text by turning words into vectors and measuring how close their directions are. It ignores the length of the text, so it focuses on the meaning or topic similarity rather than size.

beginner

What does a cosine similarity score of 0 mean?

A cosine similarity score of 0 means the two vectors are at a 90-degree angle, so they have no similarity or relation in direction.

intermediate

Can cosine similarity be negative? What does that mean?

Yes, cosine similarity can be negative, down to -1. A negative score means the vectors point in opposite directions, showing opposite or very different meanings.

What is the range of cosine similarity values?

A -0.5 to 0.5

B 0 to 1

C -1 to 1

D 0 to 100

Cosine similarity ranges from -1 (opposite) to 1 (same direction).

Which part of the cosine similarity formula measures the length of a vector?

A Magnitude (length)

B Difference of vectors

C Sum of elements

D Dot product

Magnitude measures the length of a vector and is used to normalize the dot product.

Why is cosine similarity preferred over Euclidean distance for text similarity?

A It ignores vector length, focusing on direction

B It is faster to compute

C It works only with numbers

D It measures exact word matches

Cosine similarity focuses on the angle (direction) between vectors, ignoring length differences.

If two text vectors have a cosine similarity of 1, what does it mean?

A They are completely different

B They have no words in common

C They are orthogonal

D They are identical in direction

A cosine similarity of 1 means the vectors point in the exact same direction.

What does a cosine similarity of 0 indicate about two vectors?

A Vectors are identical

B Vectors are orthogonal (no similarity)

C Vectors are opposite

D Vectors have negative correlation

A score of 0 means the vectors are at right angles, showing no similarity.

Explain in your own words what cosine similarity measures and why it is useful in comparing text data.

Think about how you compare two sentences by their meaning, not length.

Describe how you would calculate cosine similarity between two word vectors step-by-step.

Remember the formula: (A · B) / (||A|| * ||B||).