Scalar operations on arrays in NumPy - Cheat Sheet & Quick Revision

Recall & Review

beginner

What happens when you add a scalar to a NumPy array?

The scalar is added to each element of the array individually. This is called broadcasting.

beginner

How does multiplying a NumPy array by a scalar affect the array?

Each element in the array is multiplied by the scalar, scaling all values by that number.

beginner

What is the result of subtracting a scalar from a NumPy array?

The scalar is subtracted from each element of the array, reducing each value by that scalar.

beginner

Can you divide a NumPy array by a scalar? What happens?

Yes, dividing a NumPy array by a scalar divides each element by that scalar, scaling down the values.

intermediate

Why are scalar operations on arrays useful in data science?

They allow quick and easy element-wise transformations on datasets without writing loops, making code simpler and faster.

What does adding a scalar to a NumPy array do?

A Adds the scalar to the array shape

B Adds the scalar only to the first element

C Adds the scalar to each element of the array

D Throws an error

Adding a scalar to a NumPy array adds that scalar to every element individually.

If you multiply a NumPy array by 0, what is the result?

A An error occurs

B The array remains unchanged

C Each element doubles

D Each element becomes 0

Multiplying by 0 sets every element in the array to 0.

Which operation scales all elements of a NumPy array by the same number?

A Adding a scalar

B Multiplying by a scalar

C Changing the array shape

D Subtracting a scalar

Multiplying by a scalar scales all elements by that number.

What happens if you divide a NumPy array by 1?

A Each element is divided by 1, so the array stays the same

B Each element becomes 1

C Each element doubles

D An error occurs

Dividing by 1 leaves each element unchanged.

Why are scalar operations on arrays preferred over loops in NumPy?

A They are faster and use less code

B They are slower but easier to write

C They require more memory

D They only work on 1D arrays

Scalar operations use optimized code internally, making them faster and simpler than loops.

Explain how scalar addition works on a NumPy array and why it is useful.

Think about how adding one number affects every item in a list.

Describe the effect of multiplying a NumPy array by a scalar and give a real-life example.

Imagine increasing all prices by 10%.