The LAYOUT LATTICE Statement

The LAYOUT LATTICE statement defines a multi-cell grid of graphs that can automatically align plot areas and tick display areas across grid cells to facilitate data comparisons among plots. The LATTICE layout differs from the classification panel layouts in that the number of cells must be predefined and that you must define the content of each cell separately. LATTICE is superficially similar to a GRIDDED layout because it can create a grid of heterogeneous plots. However, the LATTICE has much more functionality and supports the following:

adjustable column and row sizes
axis equalization on a row or column basis to facilitate comparisons
internal axes on a per-cell basis, or external axes for rows or columns of cells
internal labeling of cell contents (cell header)
external labeling of rows and columns (column and row headers)
external sidebars that span all columns (top and bottom) or rows (left and right).

LATTICE Layout with Internal Axes shows a four-cell grid (two rows and two columns). It was produced with a LATTICE layout to illustrate the features of this layout type. The figure contains definitions of four plots, which by default are treated independently.

A mixture of plot types or nested layouts could be used in the cells of the lattice. By default, each plot manages its own axes internal to the lattice boundaries. In the figure, a light gray border has been added to each plot to show its boundaries within the lattice. The shaded areas represent the optional features that you can add to the lattice definition. By default, these shaded areas are not used in the lattice and space is not reserved for them. Thus, in the default case, the plot areas would expand to replace the shaded areas in the cells.

LATTICE Layout with Internal Axes

The shaded areas that are shown in the figure are typically used as follows:

Cell Headers are commonly used to describe the contents of a cell. Notice that the cell header, when present, has a separate space above the plot wall area. The cell header can contain more than one line of text, but it is not restricted to displaying text. For example, you could use this area to display a legend.
Sidebars are often used to present text or a legend that pertains to all rows or all columns in the grid. Again, the sidebar is not limited to text or a legend. You could place another plot in a sidebar.
Column Headers and Row Headers present text that pertains to individual columns and rows. These header areas can also be used to display other components, like legends and plots.

LATTICE Layout with External Axes shows how the lattice would look if you used additional options to externalize the axes. The figure externalizes both the row and column axes, but you could externalize the axes only for the rows, or only for the columns. When axes are external to the cells, the scale of the data ranges that are displayed for the plots are always unified in some form. Unifying the scale of the data ranges means taking the minimum of all data minima and the maximum of all data maxima from a set of plots. The following variations are available for unifying the axes:

the scale of the data ranges of all X-axes in a column can be unified on a per-column basis, or unified across all columns. (See "Column 1 Axis" and "Column 2 Axis" in LATTICE Layout with External Axes.)
the scale of the data ranges of all Y-axes in a row can be unified on a per-row basis, or unified across all rows. (See "Row 1 Axis" and "Row 2 Axis" in LATTICE Layout with External Axes.)

By default, external axes are displayed only on the primary axes (bottom and left). They are not displayed on the secondary axes (top and right) unless requested. Notice that external axes use less space and result in larger plot areas than internal axes. (Compare LATTICE Layout with External Axes with LATTICE Layout with Internal Axes, which is the same size.)

LATTICE Layout with External Axes

The following example shows a very simple LATTICE layout:

proc template;
  define statgraph intro;
    begingraph;
      entrytitle "Two-Cell Lattice Layout";
      layout lattice;
        barchart x=age;
        scatterplot x=height y=weight;
      endlayout;
    endgraph;
  end;
run;

proc sgrender data=sashelp.class template=intro;
run;

In a LATTICE layout, each plot statement is considered independent and is placed in a separate cell. When no grid size is provided, the default layout creates a graph with one column of cells, and it allots each cell the same amount of space. The number of rows in the grid is determined by the number of stand-alone plot statements in the layout block.