D3HISTOGRAM directive

Plots three-dimensional histograms.

Options

TITLE = text

General title; default *

WINDOW = scalar

Window number for the plots; default 1

KEYWINDOW = scalar

Window number for the key (zero for no key); default 2

ELEVATION = scalar

The elevation of the viewpoint relative to the surface; default 25 (degrees)

AZIMUTH = scalar

Rotation about the horizontal plane; the default of 225 degrees ensures that, with a square matrix M, the element M$[1;1] is nearest to the viewpoint

DISTANCE = scalar

Distance of the viewpoint from the centre of the grid on the base plane; default * gives a distance of 100 times the maximum of the x-range and the y-range

SCREEN = string

Whether to clear the screen before plotting or to continue plotting on the old screen (clear, keep); default clea

KEYDESCRIPTION = text

Overall description for the key; default *

ENDACTION = string

Action to be taken after completing the plot (continue, pause); default * uses the setting from the last DEVICE statement

Parameters

GRID = identifier

Pointer (of variates representing the columns of a data matrix), matrix or two-way table specifying values on a regular grid

PEN = scalar

Pen number to be used for the plot; default 1

DESCRIPTION = texts

Annotation for key

Description

D3HISTOGRAM plots a surface as a three-dimensional (or bivariate) histogram. The surface is represented by a grid of z-values or heights. The grid can be a rectangular matrix, a two-way table or a pointer to a set of variates; the y-dimension is represented by the rows of the structure and the x-dimension by the columns. In each case there must be at least three rows and three columns of data (after allowing for any restrictions on a set of variates). Missing values are not permitted; that is, only complete grids can be displayed. If the grid is supplied as a table with margins, these will be ignored when plotting the surface.

The position of the point from which the histogram is viewed is specified in polar coordinates, using the options ELEVATION, DISTANCE and AZIMUTH. These define the angle of elevation, in degrees, above the base plane of the surface, distance from the centre of this plane, and angular position relative to the vertical z-axis, respectively, similarly to the DSURFACE directive.

The TITLE, WINDOW, SCREEN and ENDACTION options are used to specify a title, the plotting window, whether the screen should be cleared first, and whether there should be a pause once the plotting is finished; as in other graphics directives (see, for example, DGRAPH). Similarly, the KEYWINDOW and KEYDESCRIPTION options and the DESCRIPTION parameters allow a key to be defined, if feasible for these plots with the current graphics device.

The PEN parameter specifies the pen to be used to plot the histogram (by default, pen 1). The PEN directive can be used to modify the colour and the thickness of the pen, but the other attributes of the pen are ignored.

Simple axes are drawn to indicate the directions in which x and y increase. The TITLE parameter of the XAXIS and YAXIS directives can be used to add further annotation.

Options: TITLE, WINDOW, KEYWINDOW, ELEVATION, AZIMUTH, DISTANCE, SCREEN, KEYDESCRIPTION, ENDACTION.

Parameters: GRID, PEN, DESCRIPTION.

Action with RESTRICT

D3HISTOGRAM takes account of restrictions on any of the variates in a GRID pointer.