Frequently Asked Questions

How do I access an Attribute value?

 int a = attr.getValue();   // get the 
   

How do I set an Attribute value ?

  sc_attr.setValue(1.45);       // scalar attribute
  arr_attr.setValue(2, 12);      // set Array element 2 to value 12

How do OMS Arrays relate to IEEE data types

How do I declare a dynamic 1D float array

  /** Array example
   * @oms.dim d
   */
  Attribute.FloatArray  arr;

Note: if the @oms.dim info is missing the array will be a 1D array per default.

How do I declare a dynamic 2D double array

  /** Array example
   * @oms.dim x,y
   */
  Attribute.DoubleArray  arr;

Note: Different dimensions are specified only in the meta data sections, All using the same array class.

How do I declare a static 1D float array?

  /** Array example
   * @oms.dim x:10
   */
  Attribute.FloatArray  arr;

Note: Such an array usually maps to a FORTRAN array, which is statically allocated. Therefore any change in the length would cause an improper access to memory at the FORTRAN level.

How do I get the rank of an array?

  /** Array example
   * @oms.dim x,y
   */
  Attribute.FloatArray  arr;
  ...
  int rank = arr.getRank();  // 2

How do I get the actual dimension length?

  /** Array example
   * @oms.dim x,y
   */ 
  Attribute.FloatArray  arr;
  ...
  int[] dims = arr.getDims();
  System.out.println(dims.length);   // ouput: 2
  System.out.println(dims[0]);   // ouput: 0
  System.out.println(dims[1]);   // output: 0

The second example shows the same code for a static array:

  /** Array example
   * @oms.dim x:2,y:3
   */
  Attribute.FloatArray  arr;
  ...
  int[] dims = arr.getDims();
  System.out.println(dims.length);   // ouput: 2
  System.out.println(dims[0]);   // ouput: 2
  System.out.println(dims[1]);   // output: 3

How do I allocate a dynamic array?

  /** Array example
   * @oms.dim x,y
   */
  Attribute.FloatArray  arr;
  ...
  int[] dims = arr.getDims();
  System.out.println(dims.length);   // ouput: 2
  System.out.println(dims[0]);   // ouput: 0
  System.out.println(dims[1]);   // output: 0

  arr.allocate(new int[] {5,6});
  System.out.println(dims.length);   // ouput: 2 
  System.out.println(dims[0]);   // ouput: 5
  System.out.println(dims[1]);   // output: 6

Note: If the number of dimensions used in the allocate() call is different from the one specified in the @oms.dim section, an IllegalArgumentException is thrown. If the array is static, the allocate() call throws an IllegalAccessException

How do I access Array Elements?

  /** Array example
   * @oms.dim x:2, y:3
   */
  Attribute.FloatArray  arr;
  ...
  int[] dims = arr.getDims();
  assert dims.length==1 : "Invalid dimensions for arr";
  for(int i = 0; i<dims[0]; i++) {
    for(int j = 0; j<dims[1]; j++) {
      // printing out the existing Value
      System.out.println(Element "+i+","+j+ arr.getValue(i,j);
      // setting the value
      arr.setValue(i,j, 10 + i+ j);
    }
  }
  

How do I accessing the array store?

  /** Array example
   * @oms.dim x:2, y:3
   */
  Attribute.FloatArray  arr;
  ...
  Array.Store store = arr.getStore();    

  System.out.println(store.size())  // 6
  float sum = 0;
  for(int i = 0; i<store.size(); i++) {
    sum += store.getDouble(i);
  }
  System.out.println("Mean: " + sum/store.size());
  

Notes

• There is clear distinction between the dimension rank (or shape) and the dimension lengths. As someone might notice there is no way in the OMS API that you can change the shape of an array programmatically. What should be the use case? There is none. Code is always written against a certain array shape.

• OMS Arrays are not dynamic regarding their layout, they are mutable to the length of their dimension only. In other words: You cannot change a one dimensional array into a two dimensional array, but you can change the length of any array dimension; that's what dynamic means.
• Static arrays as proposed are not allowing for any change at all, even dimension lengths are fixed! Reason: They are mapped to static allocated FORTRAN array.