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graph
Format: graph( data, x, style, title,
xlabel, ylabel, legend )
Arguments: [real] data Y-data points
[any] x Optional x-data points; default = 1..n
[int] style Optional style declaration for graph of the
corresponding data set; default = GS_DEFSTYLE
(text) title Optional graph title; default = null
(text) xlabel Optional x-axis label;
default = null
(text) ylabel Optional y-axis label;
default = null
[text] legend Optional label for each y-data set;
default = null
Returns: null
Description: Graph can be used to produce a graphic
representation of a set of data points. Any number of traces can
be displayed on the same graph by specifying more than one set of
y-data points. Also, the style of each trace can be declared
independently; so, you can mix line plots, scatter plots, etc.,
on the same graph.
The x- and y-data points are specified in parallel lists. The
first element in the x-list and the first element in the y-list
together make up one data point. Likewise, the second elements in
each list together make up the second point, and so on. If more
than one data trace is to be graphed, compose the data
argument as a list of lists; e.g., [y1,y2,y3] where each yn
is a list of data for one trace. If the x argument
contains only one list, these values are used for all data
traces. Otherwise, the x argument must contain a list of
x-value for each trace; e.g., [x1,x2,x3].
The type of graph created (line, bar, scatter, etc.) is
declared by the style argument. This argument is an
integer or list of integers that declare the style used to plot
the corresponding data set. That is, the first number in the style
list defines how the y1-data set is plotted, the second
number in the style list defines the y2 set and so
on. If there are fewer style elements than there are y-data sets,
the last style is repeated for all remaining sets. This means
that if only one style number is supplied, it defines the style
for all data sets. The first style element defines not only the
style of the first data set, but also defines several attributes
about the entire graph such as turning the grid on or off.
The style arguments for the table, graph, and graph3 primitives are all
constructed by adding together a series of pre-defined constants.
These constants turn particular attributes on or off. For
example, the default graph style, GS_DEFSTYLE, is defined as
GS_LINE + GS_GRID + GS_AXES + GS_COLOR. Each of these style
constants and all others that can be used are described in the
following table:
Global Graph Styles:
GS_LOGX Use a logarithmic x-axis scale; all x-values must be
greater than zero.
GS_LOGY Use a logarithmic y-axis scale; all y-values must be
greater than zero.
GS_ZERO Include zero in the y-axis. The y-axis range is
normally selected automatically to include all y-values. This
option forces zero to be included in the y-range.
GS_BOX Draw a bounding box around the graph. This and the
GS_GRID style force axes to be placed at the left and bottom
edges of the graph rather than in the graph interior.
GS_AXES Draw x- and y-axes. Same as GS_AXISX + GS_AXISY.
GS_AXISX Draw x-axis.
GS_AXISY Draw y-axis.
GS_GRID Draw a grid. Same as GS_GRIDX + GS_GRIDY. This and the
GS_BOX style force axes to be placed at the left and bottom edges
of the graph rather than in the graph interior.
GS_GRIDX Draw a grid in the x-direction.
GS_GRIDY Draw a grid in the y-direction.
GS_ASPECT Use the same scale factor to adjust both the x- and
y-axes. Normally, axes are scaled to fit the window or page on
which the graph is drawn. Selecting this style forces one unit in
the x-direction to be exactly the same physical length as one
unit in the y-direction.
GS_COLOR Use color to distinguish different traces on the
graph. Normally, hatch patterns or dotted lines are used.
GS_AUTO Automatically reconstruct the graph if any nodes in
the system change. Without this option you can explicitly update
a graph by clicking the Recalculate button.
GS_STACKED Stack successive data sets and plot the sums. The
first trace is based on the y1-data set only. The second trace is
based on the sum of the y1- and y2-sets; and so on. The final
trace represents is the sum of all y-data sets.
Individual Trace Styles:
GS_AREA Shade the area beneath a line graph
GS_LINE Connect points with a straight line
GS_POINT Plot the data points
GS_BAR Create a bar graph. With bar graphs, the x-axis is not
drawn to scale, but instead, each x-point is allocated the same
space across the x-axis
GS_DELTA Draw a vertical arrows whose height represents
magnitude in the y-direction
GS_VALUE Display the y-value above each point
Examples: x:=[1,2,3,4]
y1:=[3,7,12,15]
y2:=[9,10,10,12]
graph([y1,y2],x,GS_BAR+GS_AXES,"Sales","Year","Millions",
["ABC","XYZ"])
See Also: graph3, table
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