Graph queries are used to analyse the actual structure (graph), which can be for example a plant structure.

In XL, queries are enclosed in asterixed parentheses (* *).

The elements in a query are given in their expected order, e.g. (* A A B *) searches for a subgraph which consists of a sequence of nodes of the types A A B, connected by successor edges.

To try out how queries work, we first create a simple plant model.

module Bud extends Sphere(0.1).(setShader(GREEN));
 
module Internode(int age, super.length) extends Cylinder(length, 0.1).(setShader(YELLOW));
 
module Leaf(int age, super.length, double width) extends Parallelogram(length, width).(setShader(GREEN)) 
{
    double area;
 
    { setArea(); }
 
    void setArea() {
        area = length*width;
    }
}
 
protected void init()
[
    Axiom ==> Bud;
]
 
public void run()
[
    Bud ==> 
        Internode(1, 1) 
        [RL(60) Leaf(1, 1, 1)] 
        RH(180)
        Bud
    ;
 
    i:Internode ::> { i[age]++; i[length] += 1; }
    l:Leaf ::> { l[age]++; l[length] += 1; l.setArea(); }
]

We create a new method called analyse(). The method will appear as a new button in the RGG toolbar. Inside this method, we first call the run() method for 3 steps. The result is a simple plant made of 3 internodes and 3 leaves.

public void analyse()
{
    for (apply(3)) { run(); }
 
    println("add here a query example");
}

Replace the text inside the println() one by one by the queries below.

To list all the internodes in the structure:

(* Internode *)