Diminishing the Size of a Matrix :: Data Structures (Programming)

Programming

Diminishing the Size of a Matrix

You can delete rows and columns from a matrix by assigning the empty array [] to those rows or columns. Start with

A = magic(4)
A =
    16     2     3    13
     5    11    10     8
     9     7     6    12
     4    14    15     1

Then, delete the second column of A using

```
A(:, 2) = []
```

This changes matrix A to

A = 
   16    3   13
    5   10    8
    9    6   12
    4   15    1

If you delete a single element from a matrix, the result isn't a matrix anymore. So expressions like

```
A(1,2) = []
```

result in an error. However, you can use linear indexing to delete a single element, or a sequence of elements. This reshapes the remaining elements into a row vector:

```
A(2:2:10) = []
```

results in

A = 
    16     9     3     6    13    12     1

Resizing and Reshaping Matrices Reshaping a Matrix