MATLAB Programming/Struct Arrays
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[edit] Introduction to Structures
MATLAB provides a means for structure data elements. Structures are created and accessed in a manner familiar for those accustomed to programming in C.
MATLAB has multiple ways of defining and accessing structure fields. See Declaring Structures for more details.
Follow this link for MATLAB structure help.
Note: Structure field names must begin with a letter, and are case-sensitive. The rest of the name may contain letters, numerals, and underscore characters. Use the namelengthmax function to determine the maximum length of a field name.
[edit] Declaring Structures
Structures can be declared using the struct command.
>> a = struct('b', 0, 'c', 'test')
a =
b: 0
c: 'test'
In MATLAB, variables do not require explicit declaration before their use. As a result structures can be declared with the '.' operator.
>> b.c = 'test'
b =
b: 0
c: 'test'
Structures can be declared as needed and so can the fields.
[edit] Arrays of Structures
Structures can also be arrays. Below is an example
>> a = struct('b', 0, 'c', 'test'); % Create structure
>> a(2).b = 1; % Turn it into an array by creating another element
>> a(2).c = 'testing'
a =
1x2 struct array with fields:
b
c
>> a(1) % Initial structure
ans =
b: 0
c: 'test'
>> a(2) % The second element
ans =
b: 1
c: 'testing'
[edit] Accessing Fields
When the field name is known the field value can be accessed directly.
>> a.c
ans =
test
ans =
testing
In some cases you may need to access the field dynamically which can be done as follows.
>> str = 'c';
>> a(1).(str)
ans =
test
>> a(1).c
ans =
test
[edit] Accessing Array Elements
Any given element in a structure array can be accessed through an array index like this
>> a(1).c
ans =
test
To access all elements in a structure array use the syntax {structure}.{field}. In order to get all values in a vector or array use the brackets ([]) as seen below.
>> [a.('c')]
ans =
testtesting
>> [a.('b')]
ans =
0 1
