PLOT <data> / TYPE=FACES
plots multidimensional data as Chernoff's faces.
Reference: Chernoff,H.(1973) Using faces to represent points in
k-dimensional space graphically, JASA,68,361-368.
The mapping from data to various features of the face is defined by a
VARIABLES list written after the PLOT line.
To create this list, it is best to activate PLOT (with TYPE=FACES)
without any list. Then a model of the list with appropriate comments
will be displayed below the current PLOT line.
A typical list is following:
PLOT <data> / TYPE=FACES
VARIABLES: xmin xmax Features fmin fmax
<X1> <min X1> <max X1> Radius_to_corner_of_face_OP 0.6 1.0
<X2> <min X2> <max X2> Angle_of_OP_to_horizontal 0.0 0.6
<X3> <min X3> <max X3> Vertical_size_of_face_OU 0.6 1.0
<X4> <min X4> <max X4> Eccentricity_of_upper_face 0.5 1.5
<X5> <min X5> <max X5> Eccentricity_of_lower_face 0.5 1.5
<X6> <min X6> <max X6> Length_of_nose 0.1 0.5
<X7> <min X7> <max X7> Vertical_position_of_mouth 0.2 0.8
<X8> <min X8> <max X8> Curvature_of_mouth_1/R -4.0 4.0
<X9> <min X9> <max X9> Width_of_mouth 0.2 1.0
<X10> <min X10> <max X10> Vertical_position_of_eyes 0.0 0.4
<X11> <min X11> <max X11> Separation_of_eyes 0.3 0.8
<X12> <min X12> <max X12> Slant_of_eyes -0.5 0.5
<X13> <min X13> <max X13> Eccentricity_of_eyes 0.3 1.0
<X14> <min X14> <max X14> Size_of_eyes 0.1 0.2
<X15> <min X15> <max X15> Position_of_pupils -0.1 0.1
<X16> <min X16> <max X16> Vertical_position_of_eyebrows 0.2 0.4
<X17> <min X17> <max X17> Slant_of_eyebrows -0.5 0.5
<X18> <min X18> <max X18> Size_of_eyebrows 0.1 0.5
END of plotting specifications
The variables selected will be mapped to various features linearly so
that xmin -> fmin and xmax -> fmax. This scheme may be freely edited
by altering xmin and ymin values (eventually also fmin and fmax) to
achieve a desired result. For example, the influence of certain variable
could be reversed by changing its xmin and xmax values.
To keep certain features constant, use character '-' instead of a
variable. Then (fmin+fmax)/2 will be used as the value of the feature
for all observations.
The default list obtained after activating PLOT with TYPE=FACES without
a list has '-' as each variable, '*' for xmin and '**' for xmax.
If now '-' is replaced by a name of a variable and PLOT is activated,
the faces are plotted by using the true minimum value value in place of
'*' and maximum value in place of '**'. (The list is automatically
updated with true values ending to '*' or '**'.)
The user may then add various features gradually and see their effects
immediately. The mapping can be fixed by erasing '*'s.
The PLOT operation for Chernoff's faces may be supported by the
extra specifications HEADER,HOME,SIZE,XDIV,YDIV as in any curve plotting
schemes.
Furthermore two special specifications LABEL and FSIZE are available.
LABEL=<label variable> selects the name of the observation to be
printed under the face. If LABEL is omitted, # of observation will be
used as default.
FSIZE=c gives the side length of the square to be used as an area for
each face. c is given in plotting units and has the default value
which is one fifth of the current width of the plot.
The specifications SIZE,XDIV,YDIV and FSIZE determine together the
layout for the faces.
On the screen (GPLOT), the various parts of the faces can be drawn with
different colors possibly depending on values of selected variables.
The face and the eyes can also be painted.
The colors are selected by adding a COLORS list (before the END line
in the VARIABLES list).
A model of such a list is obtained by activating GPLOT with TYPE=FACES
without a VARIABLES list.
M = more information on multivariate plotting
Help System (web edition)