The data that multigraph draws into the plot area is organized into one or more "plots". A plot consists of a selection (usually two) of variables to be plotted, along with information about which axes to plot them along, and the style, color, and other visual attributes of the plot.
A plot is described with the plot
element in
the mugl file.
There can be any number (zero or more)
of plot
elements in the file. Multigraph will draw the plots
in the order they appear in the mugl file.
If no plot
element is present at all, multigraph
creates a single line plot
of the data section's first variable on the horizontal axis against
the second variable on the vertical axis (or first vertical axis, if there
is more than one).
The plot
element takes no attributes, and the following
subelements:
horizontalaxis
The horizontalaxis
element indicates which variable should be mapped to the horizontal
axis in the plot. It has no attributes, and takes a sequence of variable
subelements.
Each variable
subelements has a single attribute named ref
whose
value should be the id of a variable from the data
section. Most plots
have just one variable corresponding to the horizontal axis. If
a plot
has no
horizontalaxis
element, it defaults to using the first variable from
the data
along the horizontal axis.
verticalaxis
The verticalaxis
subelement indicates which variable(s) should be mapped to the vertical
axis in the plot. It has a single attribute named ref
whose value is the id of
one of the verticalaxis
elements specified earlier in the file. If this attribute
is missing, or if
The verticalaxis
subelement is missing altogether, the plot will use the first
vertical axis mentioned in the file (or a default one if none is mentioned).
The verticalaxis
subelement takes a sequence of variable
subelements.
Each variable
subelement has a single attribute named ref
whose
value should be the id of a variable from the data
section. Most plots
have just one variable corresponding to the vertical axis, but some may have more than one. For example,
a plot with error bars would have two "vertical axis" variables: one for the value, and another for the error
amount. If
a plot
has no
verticalaxis
element, or a
verticalaxis
with no
variable
subelements, it defaults to using the second variable from
the data
along the vertical axis.
renderer
The renderer
subelement specifies the graph style to be used for the plot.
"Renderers" are objects in the multigraph software that are responsible for drawing data
plots. Each renderer corresponds to a specific plot style, such as points, lines, bars,
and so on. The renderer
subelement has one attribute named type
,
whose value indicates the choice of renderer. New renderers that implement new plot styles
can easily be added to multigraph; Section 5.1, “Adding New Renderers” describes how to do this.
Each renderer may have options that can be specified to customize its behavior.
Options control things like color, line thickness, and other visual aspects of the plot.
Each option is given with a
option
subelement of the renderer
element.
Each option
takes two attributes:
name
and value
, which give
the name and value for that option.
At the time of this writing the supported renderers are:
Keyword | Description | Options |
line |
Standard line plot with optional dots at data points |
|
bar |
Standard bar graph |
|
fill |
Plot lines connecting data points, with a solid fill between the lines and the horizontal axis |
|
point |
Standard point plot with optional shapes (circle, square, triangle) |
|
lineerror |
Standard line plot with optional dots at data points |
|
barerror |
Standard bar graph |
|
It is possible that new renderers will have been added to multigraph since this documentation was written. You can generate a list of the current renderers that your copy of multigraph knows about, and the options they support, by writing an HTML file that creates a MultigraphRendererList instance as follows:
Example 4.2. Generating a List of Currently Supported Renderers
<html> <head> <script src="Multigraph.js"></script> </head> <body onload="new MultigraphRendererList('mydiv');"> <div id="mydiv"/> </body> </html>
To see the list of renderers available for the current copy of multigraph that is available from www.multigraph.org, visit the web page http://www.multigraph.org/renderers.