How can I get an average of different matrices stored as separate .mat files?

2 次查看（过去 30 天）

Native 2018-11-13

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/429528-how-can-i-get-an-average-of-different-matrices-stored-as-separate-mat-files

评论： João Vítor Batista Pires Santos 2021-7-20

I have 24 different matrices of dimension 68X68, stored in a folder. I need to create a new matrix that is an average of all those matrices. Using previous FAQ from this forum, I tried :

Num = 24

for i = 1:Num

files = dir(sprintf('ii_Sub*.mat',i))

for k = 1:length(files)

fprintf('Current file : %s\n', files(k).name)

a = load(files(k).name)

meanmatrix = mean(a,24)

end

This is creating a 1X1 struct only, while the mean command shows an error as well. How best can I go about it?

3 个评论
显示 1更早的评论隐藏 1更早的评论

Stephen23 2018-11-13

@Native: please do not close threads that have already have answers.

Native 2018-11-13

编辑：Native 2018-11-13

Sure, I was not aware of that. Closed it thinking that the purpose of the question was solved..

As for your earlier comment, thanks for pointing out the fallacies. I must admit that i have started to know the language of code only for a month now, so work in progress. Hope to learn a lot from this forum! :)

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Stephen23 2018-11-13

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/429528-how-can-i-get-an-average-of-different-matrices-stored-as-separate-mat-files#answer_346639

编辑：Stephen23 2018-11-13

在 MATLAB Online 中打开

Assuming that each file contains exactly one variable (a matrix) and that all matrices are the same size and type:

S = dir('*.mat');
N = numel(S);
C = cell(1,N);
for k = 1:N
    T = load(S(k).name)
    C(k) = struct2cell(T);
end
M = cat(3,C{:})
mean(M,3)

9 个评论
显示 7更早的评论隐藏 7更早的评论

Stephen23 2018-11-13

编辑：Stephen23 2018-11-13

在 MATLAB Online 中打开

"I'd like to know the logic behind what you did."

Sure, here is each line explained:

S = dir('*.mat');            % find all |.mat| files in the current directory.
N = numel(S);                % count those files.
C = cell(1,N);               % preallocate a cell array for the loaded data.
for k = 1:N                  % loop over the number of files. 
    T = load(S(k).name)      % load file data.
    C(k) = struct2cell(T);   % convert structure to cell, allocate to cell array.
end                          % end of loop
M = cat(3,C{:})              % concatenate all MxN matrices into MxNxP array
mean(M,3)                    % mean along third dimension P, giving MxN matrix

"How can I check that the ans obtained is indeed the average of all the matrices?"

Exactly the same way that you would check any other tool or process: by hand yourself, or by using another method. You can easily go through the files, pick the same element from each file (e.g. the first one) and calculate the mean yourself.

"Thanks a lot :)"

Remember to accept my answer if it helped you! Accepting an answer is the easiest way to thank the volunteers who help you on this forum.

Stephen23 2021-7-20

在 MATLAB Online 中打开

@João Vítor Batista Pires Santos: you could try something like this:

for k = 1:N 
    C{k} = ncread(S(k).name,'PRMSL_L101'); % PRMSL_L101 = Pressure (17x17x4)
end
A = cat(4,C{:});
M = mean(A,4)

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

João Vítor Batista Pires Santos 2021-7-20

@Stephen Cobeldick It works perfectly!! Thank you!

请先登录，再进行评论。

类别

MATLAB Language Fundamentals Matrices and Arrays Creating and Concatenating Matrices

在 Help Center 和 File Exchange 中查找有关 Creating and Concatenating Matrices 的更多信息

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by

How can I get an average of different matrices stored as separate .mat files?

3 个评论
显示 1更早的评论隐藏 1更早的评论

采纳的回答

9 个评论
显示 7更早的评论隐藏 7更早的评论

更多回答（0 个）

另请参阅

类别

标签

Community Treasure Hunt

How can I get an average of different matrices stored as separate .mat files?

3 个评论 显示 1更早的评论隐藏 1更早的评论

采纳的回答

9 个评论 显示 7更早的评论隐藏 7更早的评论

更多回答（0 个）

另请参阅

类别

标签

Community Treasure Hunt

WeChat

3 个评论
显示 1更早的评论隐藏 1更早的评论

9 个评论
显示 7更早的评论隐藏 7更早的评论