How to unterstand "children" in SciLab?

Question

clc
 x = [1:1:10];
 y1 = x;
 y2 = 2*x;
 y3 = 3*x;
 plot2d(x,y1);
 plot2d(x,y2);
 plot2d(x,y3)


gca().children(1).children(1).thickness = 2
gca().children(2).children(1).thickness = 7
gca().children(3).children(1).thickness = 4

I am new from Matlab to Scilab

Could someone tell me, how to unterstand children?

What means

gca().children ?

gca().children.children ?

gca().children.children(1) ?

gca().children(1).children ?

How can we know which attribute belong to children ?

e.g gca().children(1).children(1).color = ... // not exist

I am very confused now.. Thanks in Advance

Answer 1

Let's schematize the nested graphical object by their children properties.

We have

figure (f)
- axes (a)
  - compound1 (c1)
    - polyline (p1)
  - compound2 (c2)
    - polyline (p2)
  - compound3 (c3)
    - polyline (p3)

Since gca is a function lets do a = gca() because gca().children will raise an error because scilab doesn't understand that you're trying to access to the fields of its return value.

1. gca() returns the handles to the axes of the current figure :a.
2. a.children returns the array of handles of all the children of theses axes. : c1, c2, c3
3. a.children.children returns the array of handles of all the children of the above objects: p1, p2, p3
4. a.children.children(1) returns the first children of c1, c2, c3 : p1
5. a.children(1).children returns all the children of the first children of the current axes (c1). Since there only one : p1

To access the value of your entities

Either go for a temp variable :

a = gca();
idcolor=a.children(1).children(1).foreground // gives the color of a.c1.p1

or use get

// idcolor is an array , with idcolor(i) the color of pi
idcolor = get(get(get(gca(),'children'),'children'),'foreground') 

FYI

gce() command returns the handle of the last object created. With plot2d its a compound so we need to get its children.

you could rewrite your program as

clc
x = [1:1:10];
y1 = x;
y2 = 2*x;
y3 = 3*x;
plot2d(x,y1);
e1 = get(gce(),'children');
plot2d(x,y2);    
e2 = get(gce(),'children');
plot2d(x,y3)
e3 = get(gce(),'children');
e1.thickness = 2
e2.thickness = 7
e3.thickness = 4