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6.1.1 Structure Arrays

A structure array is a particular instance of a structure, where each of the fields of the structure is represented by a cell array. Each of these cell arrays has the same dimensions. An example of the creation of a structure array is

x(1).a = "string1"
x(2).a = "string2"
x(1).b = 1
x(2).b = 2

which creates a 2-by-1 structure array with two fields. As previously, to print the value of the structure array, you can type its name:

octave:2> x
x =
{
  a =

  (,
    [1] = string1
    [2] = string2
  ,)

  b =

  (,
    [1] =  1
    [2] =  2
  ,)

}

Individual elements of the structure array can be returned by indexing the variable like x (1), which returns a structure with the two fields like

octave:2> x(1)
ans =
{
  a = string1
  b =  1
}

Furthermore, the structure array can return a comma separated list (see section 6.3 Comma Separated Lists), if indexed by one of its own field names. For example

octave:3> x.a
ans =

(,
  [1] = string1
  [2] = string2
,)

The function size with return the size of the structure. For the example above

octave:4> size(x)
ans =

   1   2

Elements can be deleted from a structure array in a similar manner to a numerical array, by assigning the elements to an empty matrix. For example

in = struct ("call1", {x, Inf, "last"}, 
             "call2", {x, Inf, "first"});
in (1, :) = []
=> in =
      {
        call1 =
      
        (,
          [1] = Inf
          [2] = last
        ,)
      
        call2 =
      
        (,
          [1] = Inf
          [2] = first
        ,)
      
      }