How to concatenate matrices to calculate mean

2 vues (au cours des 30 derniers jours)
Joydeb Saha
Joydeb Saha le 20 Oct 2020
Commenté : Jan le 20 Oct 2020
I have 40 matrices DJF1979_1980_125 to DJF2019_2020_125. Each matrix is 3x721x1440. I want a mean of all the matrices, that will be a single matrix. Please help.
  2 commentaires
KSSV
KSSV le 20 Oct 2020
Read about mean, you can specify the dimension along which you want mean.
Stephen23
Stephen23 le 20 Oct 2020
Modifié(e) : Stephen23 le 20 Oct 2020
"I have 40 matrices DJF1979_1980_125 to DJF2019_2020_125."
Accessing lots of numbered variables forces you into writing slow, ineffiicient, complex, buggy code:
The much better approach is to load data into an output variable
S = load(..)
and access its fields. Or use indexing with any type of array.

Connectez-vous pour commenter.

Réponses (2)

KSSV
KSSV le 20 Oct 2020
Let A be your matrix.....use
iwant = mean(A,3) ;
  8 commentaires
Joydeb Saha
Joydeb Saha le 20 Oct 2020
I think I need to write M = mean(A,3);
Joydeb Saha
Joydeb Saha le 20 Oct 2020
I think I need to write M = mean(A,1);

Connectez-vous pour commenter.


Jan
Jan le 20 Oct 2020
As Steven has mentioned already, this is the main problem:
"I have 40 matrices DJF1979_1980_125 to DJF2019_2020_125"
Do not use strange names of variables to store importand data, bevause this impedes the processing. If you load these variables from files, store them in an array instead:
List = dir('*.mat');
Data = cell(size(List));
for k = 1:numel(List)
Data{k} = load(fullfile(List(k).folder, List(k).name));
end
Then you can apply the mean() function either is another loop, or by cellfun, or concatenate the varibales in a 4th dimension at first:
AllData = cat(4, Data{:});
MeanData = mean(AllData, 3);
  3 commentaires
Stephen23
Stephen23 le 20 Oct 2020
If every mat file contain exactly one variable then you can do this inside the loop:
fnm = fullfile(List(k).folder, List(k).name);
Data(k) = struct2cell(load(fnm));
Jan
Jan le 20 Oct 2020
@Jaydeb Saha: I do not know the contents of these files. Maybe you want to import a specific variable only?

Connectez-vous pour commenter.

Catégories

En savoir plus sur Creating and Concatenating Matrices dans Help Center et File Exchange

Community Treasure Hunt

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

Start Hunting!

Translated by