How do I take an average of fields in a structure?

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Liz Web 2018-3-23

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回答： George Abrahams 2022-12-30

image.png

I have 3 fields in a structure that I want to take the average and standard deviation of. What is the simplest way to do this?

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Espen Mikkelsen 2018-3-24

could you give one example of your data?

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Answer 1

Image Analyst 2018-3-24

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One way

totalMean = mean([BindingDataToSave.TotalVirusesBound]);
totalStdDev = std([BindingDataToSave.TotalVirusesBound]);

Similar for the other 2 fields. Walter's method is probably better since it gives you all 3 means in one shot.

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Answer 2

Walter Roberson 2018-3-24

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means = structfun(@mean, BindingDataToSave, 'uniform', 0);
stds = structfun(@std, BindingDataToSave, 'uniform', 0);

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Answer 3

George Abrahams 2022-12-30

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An improvement over Walter's answer would be to use my fieldfun function on File Exchange / GitHub, which outputs a structure with the same fields as the input structure(s). That means that you can index the means and standard deviations without knowing the order of the fields (effectively columns in your attached image).

rng(1,'twister')
BindingDataToSave = struct( 'TotalVirusesBound', num2cell(rand(26,1)), ...
    'NumberGoodViruses', num2cell(rand(26,1)), 'NumberBadViruses', ...
    num2cell(rand(26,1)) );
fieldfun( @(varargin) mean([varargin{:}]), BindingDataToSave )
% ans = struct with fields:
%     TotalVirusesBound: 0.4574
%     NumberGoodViruses: 0.4675
%      NumberBadViruses: 0.4530

Although, you should probably also consider using a table and not a structure.

BindingDataToSave = struct2table( BindingDataToSave );
mean( BindingDataToSave.TotalVirusesBound )
% ans = 0.4574
varfun(@mean,BindingDataToSave)
% ans = 1×3 table
%     mean_TotalVirusesBound  mean_NumberGoodViruses  mean_NumberBadViruses
%            0.45736                 0.46752                 0.45302       