DynamicImages2

Adding Labels, Lines and Points to Dynamic Graphs: PG Code Snippet

This code snippet shows the essential PG code to add labels, lines and points to dynamically generated graphs. Note that these are insertions, not a complete PG file. This code will have to be incorporated into the problem file on which you are working.

Problem Techniques Index

PG problem file	Explanation
loadMacros("PGgraphmacros.pl");	We have no required additions to the tagging and description section of the file, and we obviously need to include PGgraphmacros.pl to do dynamic graphs.
# a graph object $gr = init_graph(-1,-1,4,4,axes=>[0,0],grid=>[5,5]); # plot a function add_functions($gr, "4-3*e^(-x) for x in <-1,4> using color:blue and weight:2"); # add a label $gr->lb( new Label(0.25,3.25,'(0,3)', 'black','center','center')); # a line $gr->moveTo(-1,1); $gr->lineTo(4,1,'black'); # and a point $gr->stamps( closed_circle(0,3,'blue') );	In the initialization part of the file, we define a [dynamically generated graph|DynamicImages]. Then we can add labels, lines and points to the graph. To add labels, we use the lb method of the graph object. The argument is a new Label object, defined by an x-coordinate, y-coordinate, label text, color, and justification. The justification can be left, center or right for the left-to-right justification, and top, center or bottom for the top-to-bottom justification. Lines are added by moving the graph "cursor" to a point and then drawing a line to a new point. And we add points by using the stamps method of the graph object. We've added a closed circle here; as might expect, open_circles are also supported.
BEGIN_TEXT \{ image( insertGraph($gr) ) \} END_TEXT	And the graph is inserted in the text portion of the problem as we'd expect any static or dynamic image to be.

Note that there is a more complete list of the plotting options available in a graph object in the CVS documentation for WWPlot and PGgraphmacros.

Problem Techniques Index