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help for scat3
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Crude 3-dimensional graphics


        scat3 xvar yvar zvar [if exp] [in range] [, rotate(#) elevate(#)
                 axistype(axis_type) axes(line_options)
                 shadow[(scatter_options)] spikes(rspike_options)
                 titlex([title_text][, marker_label_options])
                 titley([title_text][, marker_label_options])
                 titlez([title_text][, marker_label_options]) variablenames
                 separate(varname) graph_options]


Description

    scat3 draws (crude) 3-dimensional scatterplots.  It is a port to Stata 8
    of gr3 (Gould, 1991, 1993), itself partially broken since Stata 3.1 and
    dependent upon Stage for final editing.  The 3-d graph consists by
    default of data points, spikes drawn from data points to the (x,y) plane,
    axes and axis titles.


Options

    rotate(#) specifies the rotation angle in degrees (default 45).

    elevate(#) specifies the elevation angle in degrees (default 45).

        These are the angles at which the graph is projected onto your
        two-dimensional screen.  You should try different values: the
        structure of your data may be better revealed by one angle rather
        than another.  Good choices are:

                                           Resolution of
           rotate()   elevate()        x          y         z
           ------------------------------------------------------
              30          60         good       good     adequate
              45          45       adequate   adequate   adequate
              60          30         poor       poor    excellent

    axistype(axis_type) specifies the type of axes used.  Choices are table,
        the default, "table-top" axes, outside, "outside" axes, zero, axes
        meeting at (0,0,0), and minimum, axes with origin the minimum of the
        data.  The axistype may be specified by any abbreviation, down to one
        letter.

    axes() tunes the representation of the axes (by default drawn with
        clp(solid)).  It should contain options of twoway line.

    shadow specifies that instead of vertical spikes from the data points to
        the (x,y) plane, each data point is paired with a shadow point on the
        (x,y) plane. shadow() specified with arguments tunes the
        representation of the shadow points (by default drawn with
        msize(*0.5)).  It should contain options of twoway scatter.

    spikes() tunes the representation of the spikes.  It should contain
        options of twoway rspike.

    titlex(), titley() and titlez() tune the representation of the x, y and z
        axis titles, shown as marker labels with default mlabpos(0)
        mlabcolor(black) and (in the case of the z axis title)
        mlabang(vertical). Each may contain title text and/or marker label
        options. The titles will be the text supplied; or if none is
        supplied, the variable labels of the variables concerned; or if those
        are not defined, the variable names.

    variablenames overrides the option above by specifying the use of
        variable names.

    separate() indicates that observations are to be subdivided into classes
        according to a specified variable.  Each class is plotted as if it
        defined a single variable.

    graph_options are options of twoway.


Examples

    . scat3 weight length mpg

    . scat3 length width wallht, rot(30) elev(60) axistype(z) titlez(,
        mlabang(0) mlabpos(9) mlabgap(*12)) titley(, mlabpos(7) mlabgap(*7))
        title("Height, length and width of Cumbrian cirques", size(medium))
        spikes(blw(vvthin)) ms(oh)


Author

    Nicholas J. Cox, University of Durham, U.K.
    n.j.cox@durham.ac.uk


Acknowledgements

    William Gould kindly condoned this revision of his earlier program.
    David Airey made a suggestion which led to the separate() option.


References 

    Gould, W. 1991. gr3: Crude 3-dimensional graphics.  Stata Technical
        Bulletin 2: 6-8. (STB Reprints 1: 35-38)

    Gould, W. 1993. gr3.1: Crude 3-dimensional graphics revisited.  Stata
        Technical Bulletin 12: 12. (STB Reprints 2: 42-43)