How to index a cell array in a for loop

Question

Terry Poole 2022-2-26

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1659215-how-to-index-a-cell-array-in-a-for-loop

评论： Star Strider 2022-2-26

So my code works, but it will only show the first file. I have 9 files that will return an 895 x 8 array each, i'm using a for loop to index each file and generate each array, clearly i'm not indexing something correctly, any help would be appreciated.

clear all; close all; clc;
sat = {'data_base\icp_sat2.txt', 'data_base\icp_sat4.txt', ...
    'data_base\icp_sat5.txt', 'data_base\icp_sat9.txt', ...
    'data_base\icp_sat10.txt', 'data_base\icp_sat12.txt', ...
    'data_base\icp_sat17.txt', 'data_base\icp_sat23.txt', ...
    'data_base\icp_sat25.txt'};
sats = cell2mat(sat);
base_obs = [];
for i = 1:length(sat)
    fileID = fopen(sat{i}, 'r');
    base_obs = cell2mat(textscan(fileID, '%f %f %f %f %f %f %f %f'));
    fclose(fileID);
end

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Answer 1

Star Strider 2022-2-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1659215-how-to-index-a-cell-array-in-a-for-loop#answer_905285

See if:

base_obs{i} = cell2mat(textscan(fileID, '%f %f %f %f %f %f %f %f'));

produces the desired result.

.

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Terry Poole 2022-2-26

That did it! Thanks!!

Star Strider 2022-2-26

My pleasure!

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Answer 2

Stephen23 2022-2-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1659215-how-to-index-a-cell-array-in-a-for-loop#answer_905290

在 MATLAB Online 中打开

P = 'data_base';
V = [2,4,5,9,10,12,17,23,25];
N = numel(V);
C = cell(1,N);
for k = 1:N
    F = sprintf('icp_sat%d.txt'V(k));
    C{k} = readmatrix(fullfile(P,F));
end

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Answer 3

Voss 2022-2-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1659215-how-to-index-a-cell-array-in-a-for-loop#answer_905295

在 MATLAB Online 中打开

Your code is overwriting base_obs each time through the loop.

You can make base_obs a cell array, with each cell containing a matrix of data from a file:

clear all; close all; clc;
sat = {'data_base\icp_sat2.txt', 'data_base\icp_sat4.txt', ...
    'data_base\icp_sat5.txt', 'data_base\icp_sat9.txt', ...
    'data_base\icp_sat10.txt', 'data_base\icp_sat12.txt', ...
    'data_base\icp_sat17.txt', 'data_base\icp_sat23.txt', ...
    'data_base\icp_sat25.txt'};
% sats = cell2mat(sat);
base_obs = cell(1,numel(sat));
for i = 1:length(sat)
    fileID = fopen(sat{i}, 'r');
    base_obs{i} = cell2mat(textscan(fileID, '%f %f %f %f %f %f %f %f'));
    fclose(fileID);
end

Or, since all your matrices are the same size, you can make base_obs a 3D array with the third dimension corresponding to the different files:

clear all; close all; clc;
sat = {'data_base\icp_sat2.txt', 'data_base\icp_sat4.txt', ...
    'data_base\icp_sat5.txt', 'data_base\icp_sat9.txt', ...
    'data_base\icp_sat10.txt', 'data_base\icp_sat12.txt', ...
    'data_base\icp_sat17.txt', 'data_base\icp_sat23.txt', ...
    'data_base\icp_sat25.txt'};
% sats = cell2mat(sat);
base_obs = [];
for i = 1:length(sat)
    fileID = fopen(sat{i}, 'r');
    base_obs(:,:,i) = cell2mat(textscan(fileID, '%f %f %f %f %f %f %f %f'));
    fclose(fileID);
end