BuildGraph Language

The language interpreted by the BuildGraph class is (hopefully!) simple and straight forward. It is made up of about 20 reserved words, some words having multiple meanings depending on context. The best way to understand how to construct a graph definition file is to look at examples.

Context is changed using a keyword and a { } pair. In C this would be considerd the scope. Only a subset of keywords can change the context. These keywords usually define an object that must be constructed from a set of definitions examples of such objects are fonts, axis, datasets, titles, labels etc.

The BuildGraph language is not complete. Some plot features available in the class definitions are not available in the plot language.

The Interpreter

The language interpreter only recognises predefines keywords, numbers (scientific notation is recognised), the context (scope) defining braces { }, and strings delimetered by ".

Everything following the # characeter is interpreted as a comment. All blank lines are ignored.

Anything else will be reported as an error.

Context keywords

To change context a keyword is followed (and encloses context commands) by a pair of braces. An example of a new context is the font context.

 font {
                   style bold
                   name "Helvetica"
                   size 25
                  }

The font command above might itself be enclosed in the title context or label context.

GRAPH2D

This is currently one of three main contexts (like the main procedure in C). This defines the type of graph to build. A non-interactive plot using the Graph2D class.

G2DINT

The second type of plot to build. An interactive plot using the G2Dint class.

CONTOUR

The third type of plot to build. An interactive contour plot using the Contour class.

AXIS

Define an axis using keywords such as LABEL, AXIS, BOTTOM, TOP, LEFT, RIGHT, COLOR and ATTACH.

DATA

Define a data set, using keywords such as, URL, MARKER, COLOR.

CDATA

Define the data grid for a contour plot.

MARKER

In the context of a dataset this keyword will define the STYLE, COLOR and SIZE of the marker to use for the data set. In the context of GRAPH2D or G2DINT it should only contain the URL of the marker file.

TITLE

In the context of GRAPH2D, G2DINT or CONTOUR define the title of the plot. In the context of AXIS define the axis title. TITLE uses the keywords NAME, FONT and COLOR. A title example

title {
                 name "This could be a plot title or an axis title"
                 color 0 255 255
                 font { 
                        style plain
                        name "TimesRoman"
                        size 15
                       }
               }

LABEL

Only to be used in the Axis context, define the axis labels, using the keywords FONT and COLOR

FONT

Define a font using the keywords SIZE, STYLE and NAME.

GRID

Define the grid to be displayed, using the keywords ON, OFF, and COLOR.

ZERO

Define the zero line to be displayed, using the keywords ON, OFF, and COLOR.

Keywords

FUNCTION string: The function string to be parsed to the DATA ParseFunction class
Context: DATA - The function that will be used to construct the data.; CDATA - The function that will be used to construct the data.

XRANGE number number number

The number of points and the range of points to be used with the declared function to construct the data set.

xrange 100 -1.0 1.0.

number of points is 100, the range of the data is [-1.0,1.0]

Context

DATA - The range of the data to be plotted.

CDATA - The x range of the data to be contoured.

YRANGE number number number

The number of points and the range of points to be used with the declared function to construct the data set.

yrange 100 -1.0 1.0.

number of points is 100, the range of the data is [-1.0,1.0]

Context

CDATA - The y range of the data to be contoured.

SQUARE

The aspect ratio of the graph will be 1.

Context

GRAPH

G2DINT

CONTOUR

NUMBER integer

Number of contour levels to be plotted

Context

CONTOUR

LOG

Contour levels will use a log scale.

Context

CONTOUR

LLEVELS integer

The stride for the contour levels that have labels. If set to zero no labels will be displayed.

Context

CONTOUR

URL string

Should be followed by a string which is the url of the file to be loaded.

Context: MARKER - the url of the marker file to load; DATA - the url of the data file to load.

SIZE integer

Should be followed by an integer.

Context: MARKER - the size of the marker to draw.; FONT - the size of the font.

COLOR integer integer integer

Should be followed by 3 integers in the range 0 to 255. The values of red, green and blue.

Context: FONT - Color of the text; DATA - Color of the plotted data; CDATA - Color of the contours

BACKGROUND integer integer integer

Should be followed by 3 integers in the range 0 to 255. The values of red, green and blue.

Context: GRAPH - the background color of the applet; G2DINT - the background color of the applet; CONTOUR - the background color of the applet; DATA - the background color of the data window; CDATA - the background color of the data window

NAME string

Should be followed by a string.

Context: FONT - the logical name of the font; DATA - the logical name of the dataset. This is the name used in the ATTACH command to attach datasets to axis.; TITLE - the string to display in the title of the axis or the plot.

STYLE integer or keyword

Should be followed by an integer or keyword.

Context

MARKER - the integer following the STYLE keyword is the marker to use while drawing the dataset.

FONT - should be followed by one of the following keywords PLAIN, BOLD or ITALICS. In the FONT context STYLE can be repeated and as in the Font class the styles become aditive. An example of a bold-italic font is

font {
	                  name "TimeRoman"
	                  size  20
	                  style bold
	                  style italic
	                  }

BOTTOM integer or alone

Either an axis orientation command or the width of a boundary of the plot.

Context: AXIS - The orientation of the plot; GRAPH2D - followed by an integer the width of the bottom boundary of the plot

TOP integer or alone

Either an axis orientation command or the width of a boundary of the plot.

Context: AXIS - The orientation of the plot; GRAPH2D - followed by an integer the width of the top boundary of the plot

LEFT integer or alone

Either an axis orientation command or the width of a boundary of the plot.

Context: AXIS - The orientation of the plot; GRAPH2D - followed by an integer the width of the left boundary of the plot

RIGHT integer or alone

Either an axis orientation command or the width of a boundary of the plot.

Context: AXIS - The orientation of the plot; GRAPH2D - followed by an integer the width of the right boundary of the plot

Context: DATA - draw straight line segments between data points.; GRID - draw the grid; ZERO - draw the zero line

OFF

Context: DATA - don't draw straight line segments between data points.; GRID - don't draw the grid; ZERO - don't draw the zero line

ATTACH string

Attach a named dataset to an axis.

Context: AXIS - attach the named data set (defined in the DATA context using the NAME keyword) to the current axis.

PLAIN

Only to be used as a STYLE value in the FONT context.

BOLD

Only to be used as a STYLE value in the FONT context.

ITALIC

Only to be used as a STYLE value in the FONT context.