%sp_plota
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   Create an animated  3 dimensional plot of a regression surface 
   which rotates around its y axis

Description

  The %sp_plota macro will create an animated 3 dimensional plot of a 
  regression surface based on the coefficients from two predictors in  
  a regression equation.  The graph can be saved as a .gif file and 
  used in a web page.  The individual plots that make up the animated
  gif can be viewed individually in the graph window of SAS.  The code 
  for this macro should end in a semicolon in order to avoid 
  unnecessary error messages in the log file.

Syntax

  %sp_plota(outfile="c:\sp_plota.gif", data=_spinplt,
            x1lo=-10, x1hi=10, x1by=1, x2lo=-10, x2hi=10, x2by=1,
            cons=0, bx1=0, bx2=0, bx1x2=0, bx1x1=0, bx2x2=0, 
            bx1x1x2=0, bx1x2x2=0, 
            dev=gif373, title=Spin Plot, title2 = " ", 
            cmd=plot, plot=, gopt=, 
            ang_lo=0, ang_hi=360, ang_by=10); 


    _spinplt - name of dataset where data created to be plotted in 
               graph is saved
    x1lo     - the minimum value of the range of x1
    x1hi     - the maximum value of the range of x1
    x1by     - the spacing of the grid of the regression surface
    x2lo     - the minimum value of the range of x2
    x2hi     - the maximum value of the range of x2
    x2by     - the spacing of the grid of the regression surface  
    const    - the value of the constant in the regression function
    bx1      - the value of the coefficient of x1 in the regression 
               function
    bx2      - the value of the coefficient of x2 in the regression 
               function
    bx1x2    - the value of the coefficient of x1*x2 in the  
               regression function
    bx1x1    - the value of the coefficient of x1*x1 in the  
               regression function
    bx2x2    - the value of the coefficient of x2*x2 in the  
               regression function
    bx1x1x2  - the value of the coefficient of x1*x1*x2 in the 
               regression function
    bx1x2x2  - the value of the coefficient of x1*x2*x2 in the 
               regression function
    outfile  - saves the graph as a .gif file with the given name    
    data     - saves the data with the given name
    dev      - specifies the graphic device used 
    title    - the title displayed at the top of the graph
    title2   - the second title displayed at the top of the graph
               the default is to display the regression function
               used to generate the graph, to repress this 
               secondary title let title2= 
    cmd      - specifies if the graph is a plot (the data points 
               define a surface) or a scatter plot (represents 
               each data point with a specified shape, the default  
               is a pyramid)
    plot     - specifies other options for the graph, the options 
               available will depend on whether cmd was specified 
               as scatter or plot (plot is the default) 
    gopt     - specifies other goptions which can modify the 
               detailed options on the size, color or the style of 
               the plot
    ang_lo   - the starting angle of the rotation of the plot
    ang_hi   - the ending angle of the rotation of the plot
    ang_by   - the spacing of the angles by which the plot rotates  
                                           



Examples

  %sp_plota(outfile='c:\sp_plota1.gif', bx1=-2, bx1x2=-1 ); 
  
  %sp_plota(outfile='c:\sp_plota2.gif', title2= ,
           cons=1, bx1=-2, bx2=1.7, bx1x2=-.5); 

  %sp_plota(outfile='c:\sp_plota3.gif',
           cons=1, bx1=-2, bx2=1.7, bx1x2=-.5,
           x1lo=-5, x1hi=5, x2lo=-4, x2hi=4);

  %sp_plota(outfile='c:\sp_plota4.gif',
            cons=1, bx1=-2, bx2=1.7, bx1x2=-.5, plot=grid,
            title=Great Plot!, ang_by=40, gopt= delay=15);

  %sp_plota(outfile='c:\sp_plota5.gif',
            bx1=-2, bx2=1.7, bx1x2=-.5,
            title=Great Plot!, ang_by=40,
            plot= zmin=-12 zmax=18 grid );

  %sp_plota(outfile='c:\sp_plota6.gif',
            bx1=-2, bx2=1.7, bx1x2=.5,  
            plot= grid ctop=cyan cbottom=blue caxis=green); 

  %sp_plota(outfile='c:\sp_plota7.gif',
            bx1=-2, bx1x2=-.5 , cmd=scatter, 
            plot= noneedle grid shape='balloon' size=.6);          

  %sp_plota(outfile='c:\sp_plota8.gif',
            bx1=-2, bx1x2=-.5 , cmd=scatter, 
            plot= noneedle shape='spade' size=.4, gopt = border); 

  %sp_plota(outfile='c:\sp_plota9.gif', bx1=1, bx2=-2, bx1x1x2=.1);


Author

  Michael Mitchell
  mnm@ucla.edu
  UCLA Academic Technology Services
  Statistical Consulting Group
  
Also See

  See a complete example in
    http://www.ats.ucla.edu/stat/sas/examples/aw/example_graphs.htm 
    http://www.ats.ucla.edu/stat/sas/teach/reg_int/reg_int_cont.htm
  
  For more details about the cmd, plot and gopt options please refer
    to following sections in the SAS Manuals
    http://sasdocs.ats.ucla.edu/gref/z3d-plot.htm
    http://sasdocs.ats.ucla.edu/gref/zscatter.htm
    http://sasdocs.ats.ucla.edu/gref/zonschap.htm


  Also see the macro itself from 
    http://www.ats.ucla.edu/stat/sas/macros/sp_plota.sas.txt
    
           
  Also see the books (http://www.ats.ucla.edu/stat/books/ )
    Multiple Regression: Testing and Interpreting Interactions 
      by Leona S. Aiken and Steven G. West 
    Interaction Effects in Multiple Regression by James Jaccard, 
      Robert Turrisi and Choi K. Wan