Extracting data from handle objects

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Marc Laub
Marc Laub 2022-11-29
回答： Askic V 2022-11-29
Hey, I have following problem.
I have multiple handle class objects which all have a propertie which can either be a scalar or a vector/matrix.
I now need a way to extract the last values of those vactors/matrices from all objects, so that they form a vector again.
So for example:
obj(1).value1=[1,2,3];
obj(1).value2=[0,0,0;0.1,0.2,0.3;0.9,0.8,0.7];
obj(2).value1=[1,2,3,4,5];
obj(2).value2=[0,0,0,0,0;0.9,0.7,0.8,0.6,0.5;0.1,0.2,0.3,0.4,0.5];
...
I now need to extract the data like
value1_vector=[3,5];
value2_vector=[0,0.3,0.7;0,0.5,0.5];
At the same time, these vectors/matrices have no fixed length and I dont know the length at the start. So it would be better to save same as a cell? Would that make the extracting of the values above easier?
Maybe a change in the size is not preferable when in future the code might be tranfered to a mexfile, where a size change while runtime is inmpossible.
Many thanks in advance
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Marc Laub
Marc Laub 2022-11-29
Did my best to trace back the most valuable answers, except if the answer was within a comment...
Rik
Rik 2022-11-29
The best strategy for storing your data depends on what you want to do next.
Do not reject a solution with a loop out of hand. Loops are fast and are easy for Matlab (or a human) to translate to C(++).

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Askic V
Askic V 2022-11-29
Ran in:
I hope this helps a bit:
clear
clc
obj_arr = struct('value1',[], 'value2',[]);
rng(0)
% Initialize obj_array
for ii = 1:2
% generate random number of elements
nr_el = randi([2 6], 1,1);
obj_arr(ii).value1 = randi(10,1,nr_el);
obj_arr(ii).value2 = randn(nr_el,nr_el);
end
% Determine the size of obj_arr
N = length(obj_arr);
% vectors to store values
value1_vec = zeros(1, N);
value2_vec = [];
for ii = 1:N
value1_vec(ii) = obj_arr(ii).value1(end);
[r2, c2] = size(obj_arr(ii).value2);
for jj = 1:r2
value2_vec = [value2_vec, obj_arr(ii).value2(jj,c2)];
end
end
value1_vec
value1_vec = 1×2
3 8
value2_vec
value2_vec = 1×11
-0.7549 1.3703 -1.7115 -0.1022 -0.2414 0.3192 2.3505 -0.6156 0.7481 -0.1924 0.8886

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