trace - creates, deletes, or manipulates traces within a graph


    trace create <graph> [<object>] | list <graph> | [delete | store |
        clear] <graph> <trace-list>


A trace is essentially a single series, or chain of points, within a graph. This command performs several different operations on the traces within a single graph. They are as follows:

"trace create <graph> [<object>]" creates a new trace and returns its name, which is an integer index into the graph's trace() array. graph is the integer name of the graph that was returned when the graph was created and is displayed in the graph's title bar. If no object is specified, the new trace will not have one. If an object is specified, it can be either the path to a real-valued object to be graphed, such as output(3).unit(2).output, or it can be a Tcl function that returns a real value.

"trace list <graph>" returns a list of the numbers of all of the traces within the graph.

"trace delete <graph> <trace-list>" destroys all of the traces within the graph whose numbers are listed. * refers to all of the traces in the graph.

"trace store <graph> <trace-list>" stores the given traces. When a trace is stored, an inactive, transient copy of it is created (in a new color) and the original trace is cleared.

"trace clear <graph> <trace-list>" clears the given traces. When a trace is cleared, all of the points are removed from the trace. But, otherwise, the trace remains the same.

You can read more about graphs and traces in the Graphs section of the main manual.


To create a graph, add a trace to it, and change the trace's color to red, do:

    lens> set g [graph create]
    lens> set t [trace create $g error]
    lens> setObject graph($g).trace($t).color red
    lens> graph refresh $g


graphObject, graph, exportGraph

Last modified: Wed Nov 15 10:52:38 EST 2000