MATLAB Programming Fundamentals - MathWorks

Access Data in Nested Structures

This example shows how to index into a structure that is nested within another structure.

The general syntax for accessing data in a particular field is

structName(index).nestedStructName(index).fieldName(indices)

When a structure is scalar (1-by-1), you do not need to include the indices to refer to the

single element. For example, create a scalar structure s, where field n is a nested scalar

structure with fields a, b, and c:

s.n.a = ones(3);

s.n.b = eye(4);

s.n.c = magic(5);

Access the third row of field b:

third_row_b = s.n.b(3,:)

Variable third_row_b contains the third row of eye(4).

third_row_b =

0 0 1 0

Expand s so that both s and n are nonscalar (1-by-2):

s(1).n(2).a = 2*ones(3);

s(1).n(2).b = 2*eye(4);

s(1).n(2).c = 2*magic(5);

s(2).n(1).a = '1a';

s(2).n(2).a = '2a';

s(2).n(1).b = '1b';

s(2).n(2).b = '2b';

s(2).n(1).c = '1c';

s(2).n(2).c = '2c';

Structure s now contains the data shown in the following figure.

11 Structures