`cat`

Joins arrays along a chosen dimension.

Category: Language Fundamentals > Matrices and Arrays

Syntax

C = cat(dim, A, B, ...)

Concatenates the inputs along dimension dim.

Description

cat(1, A, B) is the same as [A; B] and cat(2, A, B) the same as [A, B]. Its real use is dim 3 or higher, which brackets cannot express, for example to stack matrices into a 3-D array.

Cell arrays, strings and other array types can be joined too. If the other dimensions do not match, the call fails with a dimension error.

Input arguments

dim: Positive integer: 1 stacks vertically, 2 side by side, 3 along pages.
A, B, ...: Arrays of the same class (or compatible classes). All sizes must agree except along dim.

Output arguments

C: The joined array. Its size along dim is the sum of the input sizes.

Example

Stack two matrices into pages

A = [1 2; 3 4];
B = [5 6; 7 8];
C = cat(3, A, B);
size(C)
C(:, :, 2)

Output

ans = 1×3

     2     2     2
ans = 2×2

     5     6
     7     8

cat