Assigning multiple variables to a structure

Question

amg 2016-6-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/291146-assigning-multiple-variables-to-a-structure

评论： Steven Lord 2022-1-7

I have a collection of video clips, and for each frame of every video I calculate some stats (here, the mean R, G, and B values). I want to store this data for all the clips in a single struct, ideally by somehow assigning the variables into a struct that has the same field names. Is there a more succinct way of assigning the variables from each clip to a structure than the way I have coded it below?

Here is what I have so far:

% Initialize the struct.
  clipData = struct('meanRedLevels',cell(1,numClips),'meanBlueLevels',...
  cell(1,numClips),'meanGreenLevels',cell(1,numClips));
for clipNum = 1:length(videoList)
    % Find movie get some basic stats.
    movieFullFileName = [videoPath '/' videoList(clipNum).name ];
    vidObj = VideoReader(movieFullFileName);
    vidObjHeight = vidObj.Height;
    vidObjWidth = vidObj.Width;
    % Read in individual movie frames to a movie structure.
    mov = struct('cdata',zeros(vidObjHeight,vidObjWidth,3,'uint8'),...
        'colormap',[]);
    k = 1;
    while hasFrame(vidObj)
        mov(k).cdata = readFrame(vidObj);
        k = k+1;
    end
    numberOfFrames = size(mov, 2);
    % Initialize variables.
    meanRedLevels = zeros(numberOfFrames, 1);
    meanGreenLevels = zeros(numberOfFrames, 1);
    meanBlueLevels = zeros(numberOfFrames, 1);
    for frame = 1 : numberOfFrames
        % Extract the frame from the movie structure.
        thisFrame = mov(frame).cdata;
        % Calculate the mean R, G, and B levels.
        meanRedLevels(frame) = mean(mean(thisFrame(:, :, 1)));
        meanGreenLevels(frame) = mean(mean(thisFrame(:, :, 2)));
        meanBlueLevels(frame) = mean(mean(thisFrame(:, :, 3)));    
    end
   % Assign variables into struct with the same field names.
    clipData(clipNum).meanRedLevels = meanRedLevels;
    clipData(clipNum).meanBlueLevels = meanBlueLevels;
    clipData(clipNum).meanGreenLevels = meanGreenLevels;
end

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Answer 1

Piyush kant 2019-5-29

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https://ww2.mathworks.cn/matlabcentral/answers/291146-assigning-multiple-variables-to-a-structure#answer_377041

编辑：Piyush kant 2019-5-29

在 MATLAB Online 中打开

If a structure is defined by:

details(1).name='a';
details(2).age='29';
details(2).gender='female';

for above example multiple fields to a Struct-Array can be assigned as:

details = struct(name,'a',age,'29',gender,'female')

and if you already have name, age and gender variables in your workspace following command will suffice.

details=struct('details',{'name','age','gender'});

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Merlin Scherer 2022-1-7

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as rightly commented by Stephen,

"and if you already have name, age and gender variables in your workspace following command will suffice details=struct('details',{'name','age','gender'});",

will not generate the structure that was asked in the question.

Refer to the question Adding multiple fields and values to structure array answered by Walter Roberson for a solution.

data = struct('name', name, 'age', age, 'gender', gender, ....)

Steven Lord 2022-1-7

在 MATLAB Online 中打开

If you had field name and value cell arrays in the workspace you could use cell2struct.

names = {'name', 'hair', 'gender', 'tenure'};
values = {'Steve', 'black', 'male', 20.5};
S = cell2struct(values, names, 2)
S = struct with fields:
      name: 'Steve'
      hair: 'black'
    gender: 'male'
    tenure: 20.5000