How to accumulate values ​​from time 1 to the last time

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pink flower
pink flower 2021-9-23
编辑： Stephen23 2021-9-26
I have more than 10000 files and I want to accumulate the values of given variable between all these times and then plot it on a single image. How can I do it? The files are 1000x1000 matrices.
  2 个评论
the cyclist
the cyclist 2021-9-23
Ran in:
Let's just suppose, to keep things easy for understanding, that you only have two files, and each one has a 3x3 matrix. Suppose those two matrices are
M1 = magic(3)
M1 = 3×3
8 1 6 3 5 7 4 9 2
M2 = magic(3) + 17
M2 = 3×3
25 18 23 20 22 24 21 26 19
What exactly should the output be?
Also, what is the file type? Excel, CSV, MATLAB mat file?

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回答（2 个）

Sulaymon Eshkabilov
Here is one of the possible routines to read all 1e4 files and collect all data into a signle variable and the rest is relatively simple:
clearvars
FILE = fullfile('C:\Users\...', '*.txt'); % Directory where the files are residing. Your data file extension, e.g.: .txt, .xlsx, .csv, etc
LIST = dir(FILE);
N = length(LIST); % N = 1e4 as you stated that 1e4 files
D = zeros(1e3, 1e3, N);
for ii = 1 : N
FFName = fullfile(LIST(ii).folder, LIST(ii).name);
DATA = readmatrix(FFName);
D(:, :, ii) = DATA; % NOW D contains all data from 10000 files
end
... % Select and process the part of D that is necessary
  2 个评论
pink flower
pink flower 2021-9-26
I tried these commands, but I was unsuccessful. This was the mistake:
Error using zeros
Requested 1000x1000x48282 (359.7GB) array exceeds maximum
array size preference. Creation of arrays greater than
this limit may take a long time and cause MATLAB to
become unresponsive. See array size limit or preference
panel for more information.
Error in test (line 10)
D = zeros (1e3, 1e3, N);
Sulaymon Eshkabilov
Sulaymon Eshkabilov 2021-9-26
These are not coding problems but rather memory problems. That means either you should process your data chunk by chunk or increase the memory in your matlab settings.

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Stephen23
Stephen23 2021-9-26
P = 'absolute or relative path to where the files are saved';
S = dir(fullfile(P, '*.txt')); % Select the file extension to suit your data files
M = 0;
for k = 1:numel(S)
F = fullfile(P, S(k).name);
M = M + readmatrix(F);
end
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pink flower
pink flower 2021-9-26
For example, in row 400 and column 5, I have:
M1 = NaN;
M2 = NaN;
M3 = 0.9
And the result it returns to me is NaN. Do you understand now? If not, I can explain it better.
Stephen23
Stephen23 2021-9-26
编辑：Stephen23 2021-9-26
To ignore NaN when summing you can use SUM with the appropriate flag, e.g.:
M = zeros(1000,1000);
for k = 1:numel(S)
F = fullfile(P, S(k).name);
N = whateverCodeYouUseToImportYourFileData;
M = sum(cat(3,M,N),3,'omitnan');
end

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