vec2mat

(Not recommended) Change dimension

vec2mat is not recommended. Use reshape instead. For more information, see Version History.

Syntax

mat = vec2mat(vec,matcol)

mat = vec2mat(vec,matcol,padding)

[mat,padded] = vec2mat(___)

Description

mat = vec2mat(vec,matcol) converts vector vec to matrix mat with matcol columns. The function creates the matrix one row at a time, filling the rows with elements from vec in order. If the length of vec is not a multiple of matcol, then the function pads the last row of mat with zeros until the row contains matcol elements.

mat = vec2mat(vec,matcol,padding) specifies values for the function to use to pad the last row of mat. The function uses the value from padding in order.

[mat,padded] = vec2mat(___) also returns padded, the number of padded elements in the last row of mat. You can specify any of the input argument combinations from previous syntaxes.

Examples

Change Dimensions and Add Padding

This example uses shows you how to add padding, as needed, when converting a vector to matrix.

Create a vector that will be converted to a matrix and a vector to provide padding values.

vec = [10;20;30;40;50];
padding = [1,2;3,4;5,6];
n = 4;

When using vec2mat to convert the vector to a matrix, the function determines needed padding.

[mat4,numPadded4] = vec2mat(vec,n,padding)

mat4 =
    10    20    30    40
    50     1     3     5
numPadded4 =
     3

When using reshape to convert the vector to a matrix, the needed padding must be computed and appended to the vector before converting the vector to a matrix.

numPadded = mod(numel(vec),n);
if numPadded > 0
    numPadded = n - numPadded
    mat = reshape([vec.' padding(1:numPadded)], n, []).'
else
    numPadded % No padding required
    mat = reshape(vec.', n, []).'
end

numPadded =
     3
mat =
    10    20    30    40
    50     1     3     5

Input Arguments

vec — Input array

vector

Input array, specified as a vector.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical
Complex Number Support: Yes

matcol — Number of columns

positive integer

Number of columns for the output matrix mat, specified as a positive integer. If the length of vec is not a multiple of matcol, then the function pads the last row of mat with zeros until the row contains matcol elements.

Data Types: double

padding — Padding values

vector | matrix

Padding values for the last row of mat, specified as a vector or matrix. The padding input inherits the data type of the vec input. The function uses the values from padding in order. If padding has fewer elements than what the function needs to complete the last row of mat, then the function repeats the last element of padding until mat is full.

Output Arguments

mat — Output array

matrix

Output array, returned as a matrix with elements from vec and having matcol columns. The output inherits the data type of the input. The number of rows is equal to ceil(length(vec)/matcol).

padded — Number of padded elements

positive integer

Number of padded elements in the last row of mat, returned as a positive integer.

Version History

Introduced before R2006a

R2020a: vec2mat is not recommended

• vec2mat is not recommended. Use reshape instead.

• Given a vector input, reshape creates its corresponding matrix one column at a time (instead of one row at a time).

• reshape requires its input and output arrays to have the same number of elements, whereas vec2mat pads its output matrix if necessary.

• For an example comparing use of reshape to vec2mat, see Change Dimensions and Add Padding.