Setting multiple fields at the same time / adding a new field to the cell structure
I have a 1xn structure. Structures contain some fields with numeric cells. Not every structure has the same fields. So I would like to add the missing fields to the structure. But I didn't get it.
% Mimimal example
% I have same cells, imported from csv by csv2cell()
clear
dataCell{1}={"field_a","field_b","field_c"; ...
1,2,3; ...
4,5,6};
dataCell{2}={"field_a","field_b","field_d"; ...
1,2,4; ...
4,5,8};
% Then I convert them to a struct
for ii=1:numel(dataCell)
DataStruct{ii}=cell2struct((dataCell{ii}(2:end,:)),[dataCell{ii}(1,:)],2);
try fields=[fields, fieldnames(DataStruct{ii})']; % fails for the first loop, because 'fields' doesn't exist yet
catch
fields=[fieldnames(DataStruct{ii})']; % create 'fields' in the first loop
end
end
% Create a list of all existing fields
fields=unique(fields);
% Now look for the missing fields and add them to the struct
for jj=1:numel(DataStruct)
missing_fields{jj} = setdiff(fields,fieldnames(DataStruct{jj}));
for kk=1:numel(missing_fields)
DataStruct{jj}.(missing_fields{jj}{kk})=NaN*zeros(numel(dataCell{jj}(2:end,1)),1); % Execution fails here!
end
end
This results in an error:
Octave error
error: invalid assignment to cs-list outside multiple assignment
error: called from:
error: ~/example.m at line 29, column 44
Matlab error
Insufficient outputs from right hand side to satisfy comma separated
list expansion on left hand side. Missing [] are the most likely cause.
The problem is that the output is DataStruct{1}.field_a
not a matrix or a cell, but several ans. Is there an easy way to convert cells to matrix, or better csv import option?
Another good possibility would be like this.
DataStruct{jj}=setfields(missing_fields{jj},NaN_Values{jj})
where missing_fields{jj}
and NaN_Values
are both cells with the same length, so I can set multiple fields at once.
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You use a function deal
to distribute output to inputs. For your example:
% Now look for the missing fields and add them to the struct
for jj=1:numel(DataStruct)
missing_fields{jj} = setdiff(fields,fieldnames(DataStruct{jj}));
for kk=1:numel(missing_fields)
[DataStruct{jj}.(missing_fields{jj}{kk})] = deal(NaN*zeros(numel(dataCell{jj}(2:end,1)),1));
end
end
Note what you get Index exceeds matrix dimensions
, but this is related to a different issue - I'm sure you can sort this file!
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