function [V, Pi_idx] = Observation( folder)
    d=dir(folder);

    [lg, ~]=size(d);
    V=[];
    cpt=1;
    Pi_idx=[];
    disp(['Scan forlder: ' folder]);
    for i=3:lg
        if d(i).isdir==1
            adresse=[folder '/' d(i).name '/Data_' d(i).name '.mat'];
            disp(['  Lecture ' adresse ' en cours!']);
            Data_struc=load(adresse);
            Data_struc=Data_struc.data_g.(d(i).name);
            name_seq=fieldnames(Data_struc);
            nb_seq=size(name_seq);
            for j=1:nb_seq
                v=Data_struc.(name_seq{j}).V;
                Pi_idx=[Pi_idx cpt];
                cpt=cpt+size(v, 2);
                V=[V v];
            end
        end
    end
end

