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octave: Structure Arrays

 
 6.1.2 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.  Conceptually, a structure
 array can also be seen as an array of structures with identical fields.
 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 1-by-2 structure array with two fields.  Another way to
 create a structure array is with the ‘struct’ function (Creating
 Structures).  As previously, to print the value of the structure
 array, you can type its name:
 
      x
           ⇒ x =
              {
                1x2 struct array containing the fields:
 
                  a
                  b
              }
 
    Individual elements of the structure array can be returned by
 indexing the variable like ‘X(1)’, which returns a structure with two
 fields:
 
      x(1)
           ⇒ ans =
              {
                a = string1
                b =  1
              }
 
    Furthermore, the structure array can return a comma separated list of
 field values (Comma Separated Lists), if indexed by one of its
 own field names.  For example:
 
      x.a
           ⇒
              ans = string1
              ans = string2
 
    Here is another example, using this comma separated list on the
 left-hand side of an assignment:
 
      [x.a] = deal ("new string1", "new string2");
       x(1).a
           ⇒ ans = new string1
       x(2).a
           ⇒ ans = new string2
 
    Just as for numerical arrays, it is possible to use vectors as
 indices (Index Expressions):
 
      x(3:4) = x(1:2);
      [x([1,3]).a] = deal ("other string1", "other string2");
      x.a
           ⇒
              ans = other string1
              ans = new string2
              ans = other string2
              ans = new string2
 
    The function ‘size’ will return the size of the structure.  For the
 example above
 
      size (x)
           ⇒ ans =
 
                1   4
 
    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 =
              {
                1x3 struct array containing the fields:
 
                  call1
                  call2
              }
 
      in(1) = [];
      in.call1
           ⇒
             ans = Inf
             ans = last
 

Info Catalog octave: Basic Usage and Examples octave: Structures octave: Creating Structures