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Arrays and Clusters

Module by: Eduardo Perez. E-mail the author

Summary: The creation of this content was supported in some part by NSF grant 0538934.

To create an array in G, right click on the Front Panel window and select Array from the Controls >> Modern >> Arrays, Matrix & Cluster menu, and drop the array structure onto the Front Panel window to create an array.

Figure 1: Array Structure
An array structure. The top level listing of the array is labeled Modern and underneath that level is Array, Matrix & Cluster. This level is identified by two icons in a gray shaded rectangle. The icon on the left is labeled Array and the icon on the right is labeled Cluster.

The array structure consists of an index or element offset (highlighted left portion of the array structure) and the array elements (right portion of the structure). When the array structure is placed on the Front Panel window, the data type of the array is undefined as indicated by the grayed out portion of the array.

Figure 2: Index and Elements of an Array
A screen capture showing up and down arrow buttons to the left of field containing the number 0. The arrow buttons and the field containing the number 1 are contained within a red square box labeled index. These elements are the upper left of a square labeled Elements.

To define the array data type, drag and drop any data type, such as numeric, Boolean, string or cluster structure, onto the elements portion of the array structure.

Figure 3: Creating Arrays
An array field screen capture.

At this point, the newly defined array is an Empty or NullArray because no elements of the array have been defined. This is indicated by the grayed out data type within the elements array structure.

Figure 4: Empty Arrays
A form labeled 'Array' with two fields. each field contains the value '0'.

To define elements of an input array, select the element’s index and enter the appropriate value. Figure 5 defines a numeric array with one element at index 0.

Figure 5: Defining Array Elements
A form labeled 'Array' with two fields. The left field contains the value '0' and the right field contains '1.2345'.

G arrays are zero-based. The last element index of an N element array is N-1. Figure 6 and Figure 7 are those of a 10 element array.

Figure 6: Last Array Element
A form labeled 'Array' with two fields. The left field contains the value '9' and the right field contains '9.1011'.
Figure 7: Undefined Nth Element
A form labeled 'Array' with two fields. The left field contains the value '10' and the right field contains '0'.

An output array is created similarly to an input array with the exception that an output data type needs to be dropped into the array structure.

Figure 8: Input and Output Arrays
A form with two sets of two fields. The left form is labeled 'Numeric Input Array' with the values '0' and '0'. The right form is labeled 'Numeric Output Array' with both values being '0'.

Multidimensional Arrays

To create multidimensional arrays, click on the array’s index and select Add Dimension from the menu.

Figure 10 shows a 2-dimensional array.

Figure 9: Creating Multidimensional Arrays
An array form overlaid with a menu. The item 'Add Dimension' is highlighted in blue.
Figure 10: Multidimensional Array
An array form with three fields. The values are '9', '9.1' and '1'.

Array Operators

Figure 11: Array Operators
A 4x7 table of icons contained under the direcotry levels 'Programming' and 'Array'.

Clusters

Clusters allow users to create compound data types by aggregating various and different data types into a single unit.

Figure 12: Empty Cluster
An empty cluster field.

Select the various data types and drag them onto the cluster structure. Figure 13 shows an Error Cluster consisting of a Boolean Error, a numeric ID and a string Message data types.

Figure 13: Cluster Example
An error cluster field with a green circle labeled 'Error' and a field labeled 'ID' containing '2', and the last field is labeled 'Message' with the value 'Out of range'.

Cluster Operators

Figure 14: Cluster Operators
A 3x6 table of icons contained within the directory levels 'Programming' and 'Cluster, Class, and Variant'.

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Definition of a lens

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A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

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