Reshaping arrays in MATLAB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the reshape function do in MATLAB?

The reshape function changes the size and shape of an array without changing its data. It rearranges elements into a new dimension.

beginner

How do you reshape a 1x6 array into a 2x3 array in MATLAB?

Use reshape(array, 2, 3). This changes the array to have 2 rows and 3 columns.

beginner

What must be true about the number of elements when reshaping an array?

The total number of elements must stay the same before and after reshaping. For example, a 6-element array can be reshaped to 2x3 or 3x2, but not 4x2.

intermediate

What happens if you try to reshape an array to a size that doesn't match the number of elements?

MATLAB gives an error because the reshape function requires the total number of elements to remain constant.

intermediate

How does MATLAB fill the reshaped array?

MATLAB fills the reshaped array column-wise, taking elements from the original array in column-major order.

What does reshape(A, 3, 2) do if A is a 1x6 array?

A Changes A into a 2-row, 3-column array

B Changes A into a 3-row, 2-column array

C Flattens A into a 1x6 array

D Throws an error

The reshape function changes the shape to 3 rows and 2 columns, keeping all elements.

What must be true for reshape to work without error?

A The new shape must have the same total number of elements as the original

B The new shape must have fewer elements

C The new shape must have more elements

D The new shape must be square

The total number of elements must remain the same to reshape successfully.

If you have a 2x3 matrix, which reshape is valid?

A reshape(A, 1, 5)

B reshape(A, 4, 2)

C reshape(A, 6, 2)

D reshape(A, 3, 2)

2x3 has 6 elements, so reshaping to 3x2 (also 6 elements) is valid.

How does MATLAB fill elements when reshaping?

A Row-wise

B It reverses the order

C Column-wise

D Randomly

MATLAB fills reshaped arrays column-wise, following its column-major order.

What happens if you try reshape(A, 4, 2) on a 2x3 matrix?

A It throws an error

B It works fine

C It truncates extra elements

D It pads with zeros

Because 2x3 has 6 elements and 4x2 requires 8, MATLAB throws an error.

Explain how the reshape function works in MATLAB and what rules must be followed.

Think about how you can rearrange a box of items without adding or losing any.

Describe a real-life example that helps you understand reshaping arrays.

Imagine moving books from one shelf layout to another.