A data-driven
lattice is a multi-cell graph in which the cell data is determined by the values of one or
more class variables. Class variables are specified in the designer when the report
designer creates a report that includes the lattice. The number of cells is determined
by the unique values of the class variables. Each cell of the lattice has the same
graph elements. However, these graph elements have different values of the class variables.
The following example shows a graph with data assigned to it. The custom graph object
includes a data-driven lattice with a columnar role. The graph object allows multiple
data assignments for the Measure role.
In the report, the graph object includes a three-cell lattice of
bar charts showing
engine size and miles per gallon for different types of automobiles. The country of origin
is specified as the class variable. As a result, a cell is created for each country
of origin.
Here are the characteristics of data-driven
lattices:
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You can define up to two lattice roles: one role for the rows and another role for
the columns. When the report designer
uses the lattice in a report, the class variables are assigned to the lattice roles.
All class variables must come from a single
data source. The number of rows and columns in the graph is determined by the unique values of
the class variables.
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If you specify that the role is
required, then a report designer must assign data to the role.
If this option is not selected, then report designers can choose whether to assign
data to the role. In that case, it is possible for a graph object to have no lattice.
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Graph elements can be overlaid the same way they are overlaid in single-cell or
user-defined multi-cell graphs. When the report designer adds a lattice to a report, the overlaid
graph element is displayed in every cell.
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Properties that you specify for graph elements are applied to all of the cells of
the graph object.