[Scilab-users] question on graphic children order

[Federico Miyara]

Stéphane,

Sometimes one just needs to extract some parameter from an entity and 
indexing is a valid way to access it.

Federico


On 08/04/2019 12:18, Stéphane Mottelet wrote:
>
> Hello,
>
> Le 07/04/2019 à 10:13, Federico Miyara a écrit :
>>
>> Dear all,
>>
>> I would like to know if there is a reason for the fact that whenever 
>> new graphic objects are added to an axes, the last one that has been 
>> created is always the one with index 1 instead of n+1 (where n is the 
>> number of objects prior to new one).
>>
>> Example:
>>
>> scf(1)
>> clf(1)
>>
>> // Plot a simple two-point graph
>> plot2d([0, 1], [0, 1])
>> ax = gca()
>>
>> // Colect plotted data
>> a = ax.children(1).children.data
>>
>> // Plot a simple two-point graph
>> plot2d([0, 1],[0.5, 1.5])
>>
>> // Colect plotted data corresponding to index 1
>> b = ax.children(1).children.data
>>
>> // Colect plotted data corresponding to index 2
>> c = ax.children(2).children.data
>>
>> After the first plot we get
>>
>> a  =
>>    0.   0.
>>    1.   1.
>>
>> After the second plot we get
>>
>> b  =
>>    0.   0.5
>>    1.   1.5
>>
>> c  =
>>
>>    0.   0.
>>    1.   1.
>>
>> I would expect that b = a, i.e, once a children object has been 
>> created on the axes, it would be reasonable that its index were kept 
>> constant. The current behavior is as if each new object were inserted 
>> in the structure before the previous one instead of after it.
>
> I would say that the set of children is a stack, i.e. each new child 
> is "pushed" on top. Anyway, relying on child order seems, to me, a bad 
> idea. For example, legend takes as (optional) first argument an array 
> of handles, and not an array of child numbers.
>
> S.
>
>>
>> Regards,
>>
>> Federico Miyara
>>
>>
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