from structindex by AJ Johnson
Two mex files: structindex selects elements from all fields of a structure ....

structcat.m
%STRUCTCAT Concatination of fields of two or more structures.
%   STRUCTCAT(S1,S2,...) returns selected data elements from each field.
%   The returned structure will have all fields that are contained in the
%   input structures. Each field will be the (one-dimensional)
%   concatination of all data from the input structures containging that
%   field.
%
%   EXAMPLES:
%   s.name = {'sam','mike','john'};
%   s.income = [10000,90000,-10];
%   g.name = {'julie','carol'};
%   g.income = [15000,120000];
%   g.age = [19 64];
%   structcat(s,g)
%   ans = 
%         name: {'sam'  'mike'  'john'  'julie'  'carol'}
%       income: [10000 90000 -10 15000 120000]
%          age: [19 64]
%
%   See also STRUCTINDEX.

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