Removes points interactively from a spatial point pattern (M.A. Mugglestone, S.A. Harding, B.Y.Y. Lee, P.J. Diggle & B.S. Rowlingson).
Options
PRINT = string token |
What to print (summary, monitoring); default summ, moni |
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WINDOW = scalar |
Which graphics window to use for the plot; default 1 |
Parameters
OLDY = variates |
Vertical coordinates of each spatial point pattern; no default – this parameter must be set |
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OLDX = variates |
Horizontal coordinates of each spatial point pattern; no default – this parameter must be set |
NEWY = variates |
Variates to receive the vertical coordinates of the original points minus the deleted points of each pattern |
NEWX = variates |
Variates to receive the horizontal coordinates of the original points minus the deleted points of each pattern |
Description
PTREMOVE uses the DREAD directive to delete points from a spatial point pattern. The coordinates of the existing points must be supplied using the parameters OLDX and OLDY. These points will be plotted on the current graphics device using DPTMAP with a pen setting of SYMBOLS=1. The WINDOW option may be used to specify the graphics window to use for the plot.
The operation of DREAD may vary slightly from one system to another. The Users’ Note supplied with Genstat explains how to read points and terminate input on specific devices. The usual method for reading points is to click the left mouse button at the required position. The usual way to terminate input is to click the right mouse button. The points read using DREAD will be echoed using a pen setting of SYMBOLS=2. The coordinates of the new spatial point pattern containing the original points minus any points which have been deleted may be saved using the parameters NEWX and NEWY.
Printed output is controlled using the PRINT option. The settings available are monitoring (which prints the coordinates of the points to be deleted) and summary (which prints the coordinates of the new pattern consisting of the original points minus any that have been deleted under the headings NEWX and NEWY). The default setting is for both monitoring and summary.
Options: PRINT, WINDOW.
Parameters: OLDY, OLDX, NEWY, NEWX.
Method
A procedure PTCHECKXY is called to check that OLDX and OLDY have identical restrictions. DPTMAP is then used to draw a map of the original point pattern. The DREAD directive is used to read the coordinates of points to be deleted. Finally, the coordinates for the deleted points are removed from the original points using the SUBSET procedure and the coordinates of the undeleted points are stored in new variates.
Action with RESTRICT
If OLDX and OLDY are restricted, only the subset of values specified by the restriction will be included in the calculations.
See also
Procedure: DPTREAD, DRPOLYGON.
Commands for: Graphics, Spatial statistics.
Example
CAPTION 'PTREMOVE example'; STYLE=meta CALCULATE x,y = URAND(531647,0; 50) PTREMOVE OLDY=y; OLDX=x