Accessing Data in Structure Arrays :: Data Types (Programming)

Programming

Accessing Data in Structure Arrays

Using structure array indexing, you can access the value of any field or field element in a structure array. Likewise, you can assign a value to any field or field element. For the examples in this section, consider this structure array.

You can access subarrays by appending standard subscripts to a structure array name. For example, the line below results in a 1-by-2 structure array:

mypatients = patient(1:2)
1x2 struct array with fields:
    name
    billing
    test

The first structure in the mypatients array is the same as the first structure in the patient array:

mypatients(1)
ans = 
       name: 'John Doe'
    billing: 127
       test: [3x3 double]

To access a field of a particular structure, include a period (.) after the structure name followed by the field name:

str = patient(2).name
str =
   Ann Lane

To access elements within fields, append the appropriate indexing mechanism to the field name. That is, if the field contains an array, use array subscripting; if the field contains a cell array, use cell array subscripting, and so on:

test2b = patient(3).test(2,2)
test2b =
   153

Use the same notations to assign values to structure fields, for example,

```
patient(3).test(2,2) = 7;
```

You can extract field values for multiple structures at a time. For example, the line below creates a 1-by-3 vector containing all of the billing fields:

bills = [patient.billing]
bills =
  127.0000   28.5000  504.7000

Similarly, you can create a cell array containing the test data for the first two structures:

tests = {patient(1:2).test}
tests =
    [3x3 double]    [3x3 double]

Building Structure Arrays Using Dynamic Field Names