Handling cells which contains structures
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Hello community,
I have a question how to nicely handle cells which contain a structure. What I have is a measuerement which is saved as cell. The cell has the following structure: cell.struct.struct.value. To access a specific value I use cell{n, 1}.struct_name.value_name, where n is an index and can go up to 5000. Usually I use this construct to extract the values: cell2mat(cellfun(@(s)s.struct_name.value_name,cell_name,'uni',0)).
In this case this doesn't work since the struct is empty for some indices. Any idea how to solve this without using a for loop?
Thanks Jeremy
1 个评论
Often users places structures in cell arrays because they do not realize that structures are arrays too.
You could likely simplify your code:
- use a structure array (rather than a cell array containing structures)
- flatten the nested structures as much as possible.
You could then likely use either of these approaches:
回答（1 个）
% a cell array of structs with some stuff missing:
c = { ...
struct('field_1',struct('sub_field_1',1)) ...
struct('field_1',[]) ...
[] ...
struct('field_1',struct('sub_field_1',2)) ...
}
% the usual way gives an error in this case:
try
cell2mat(cellfun(@(s)s.field_1.sub_field_1,c,'uni',0))
catch ME
disp(ME.message);
end
% use a helper function that checks for the existence of fields:
cell2mat(cellfun(@(s)get_struct_value(s,'field_1','sub_field_1'),c,'uni',0))
% or a different helper function that puts NaNs where struct is empty, etc.:
cell2mat(cellfun(@(s)get_struct_value_with_NaN(s,'field_1','sub_field_1'),c,'uni',0))
function out = get_struct_value(s,struct_name,value_name)
if isfield(s,struct_name) && isfield(s.(struct_name),value_name)
out = s.(struct_name).(value_name);
else
out = []; % any empty struct or struct missing field returns empty array
end
end
function out = get_struct_value_with_NaN(s,struct_name,value_name)
if isfield(s,struct_name) && isfield(s.(struct_name),value_name)
out = s.(struct_name).(value_name);
else
out = NaN; % with appropriate place-holder value
end
end
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2022-11-9
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