G3GRID Procedure

Example 2: Spline and Smoothing Interpolations

Features:	GRID statement options SMOOTH= and SPLINE
Data set:	NUMS
Sample library member:	GTGSISS

This example extends Using the Default Interpolation Method to specify the SPLINE option on the GRID statement. The output data set, when used in PROC G3D, generates a smoother surface plot.

Surface Plot using Spline Interpolation (gtgsiss)

A Surface Plot Generated After Spline Interpolation

The following plot extends Using the Default Interpolation Method to specify the SPLINE option, and the SMOOTH= option on the GRID statement. The SMOOTH= option is set to .05 for additional smoothing. The output data set, when used in PROC G3D, generates a smoother surface plot.

Surface Plot using Spline Interpolation and .05 Smoothing (gtgsiss)

A Surface Plot Generated After Smoothed Spline Interpolation

Program

goptions reset=all  border;

title "Surface Plot using Spline
Interpolation";

proc g3grid data=nums out=spline;
   grid y*x=z / spline
                axis1=-5 to 5 by .5
                axis2=-5 to 5 by .5;
run;

proc g3d data=spline;
   plot y*x=z ;
run;
quit;

title "Surface Plot using Spline Interpolation and
.05 Smoothing";

proc g3grid data=nums out=smoothed;
   grid y*x=z / spline
                smooth=.05
                axis1=-5 to 5 by .5
                axis2=-5 to 5 by .5;
run;
quit;

proc g3d data=smoothed;
   plot y*x=z;
run;
quit;

Program Description

Set the graphics environment.

goptions reset=all  border;

Define the title for the plot.

title "Surface Plot using Spline
Interpolation";

Process points with PROC G3GRID. The SPLINE option specifies the bivariate spline method for the data set interpolation.

proc g3grid data=nums out=spline;
   grid y*x=z / spline
                axis1=-5 to 5 by .5
                axis2=-5 to 5 by .5;
run;

Generate the surface plot.

proc g3d data=spline;
   plot y*x=z ;
run;
quit;

Define the title for the plot.

title "Surface Plot using Spline Interpolation and
.05 Smoothing";

Process the data with PROC G3GRID.The SMOOTH=.05 option specifies the smoothing parameter to use during spline interpolation.

proc g3grid data=nums out=smoothed;
   grid y*x=z / spline
                smooth=.05
                axis1=-5 to 5 by .5
                axis2=-5 to 5 by .5;
run;
quit;

Generate the surface plot.

proc g3d data=smoothed;
   plot y*x=z;
run;
quit;