一次设置多个字段/将新字段添加到单元格结构 [英] setting multiple fields at once / add new field to a cell struct

问题描述

我有一个1xn结构.该结构包含一些带有数字单元格的字段.并非每个结构都具有相同的字段.因此，我想将缺少的字段添加到该结构中.但是我不明白.

I have a 1xn struct. The structs contains some fields with numeric cells. Not every struct has the same fields. So I would like to add the missing fields to the struct. 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

这会导致错误:

八度错误

error: invalid assignment to cs-list outside multiple assignment
error: called from:
error:   ~/example.m at line 29, column 44

Matlab错误

Insufficient outputs from right hand side to satisfy comma separated
list expansion on left hand side.  Missing [] are the most likely cause.

问题在于，DataStruct{1}.field_a的输出不是矩阵或单元格，而是多个ans.是否有将细胞转换为矩阵的简便方法，还是导入csv的更好方法?

The problem is, that the output of DataStruct{1}.field_a is not a matrix or a cell, but multiple ans. Is there a easy possibility to convert the cells to a matrix or a better possibility to import the csv?

另一个好的可能性就是这样

the other good possibility would be something like this

 DataStruct{jj}=setfields(missing_fields{jj},NaN_Values{jj})

其中missing_fields{jj}和NaN_Values都是长度相同的单元格，因此我可以一次设置多个字段.

where missing_fields{jj} and NaN_Values are both cells with the same length, so that i can set multiple fields at once.

推荐答案

您可以使用deal函数将输出分配给输入.例如:

You use the deal function 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

请注意，您会得到一个Index exceeds matrix dimensions，但这是由于另一个问题所致-我相信您将能够解决该问题！

Note that you will get an Index exceeds matrix dimensions, but this is due to a different problem - I'm sure you'll be able to sort that one out!

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