Effacer les filtres
Effacer les filtres

Save multiple columns of multiple csv files?

8 vues (au cours des 30 derniers jours)
lil brain
lil brain le 20 Jan 2022
Commenté : lil brain le 22 Jan 2022
Hi,
I have the following code:
[file_list, path_n] = uigetfile('.csv', 'Grab csv', 'Multiselect', 'on')
columns();
if ismatrix(file_list) == 0
file_list = {file_list}
end
for i = 1:length(file_list)
filename = file_list{i}
data_in = readmatrix([path_n, filename]);
% here I would like to import columns 7-27 for each file
% but instead of saving only the last iteration of the loop I want to
% save each in a new variable
columns(i) = data_in(:,7:27);
end
Every time I run this I get an error that I dont understand.
Unable to perform assignment because the left and right sides have a different number of elements.
Error in test (line 10)
columns(i) = data_in(:,7:27);
I have figured out how to get the 21 columns saved in columns but it only saves the last iteration. How do I save each iteration?
Help would be much appreciated.
  1 commentaire
Stephen23
Stephen23 le 21 Jan 2022
Simpler way to ensure that the output is a cell array of character vectors:
[file_list, path_n] = uigetfile(...);
file_list = cellstr(file_list); % <- easy

Connectez-vous pour commenter.

Réponse acceptée

Voss
Voss le 21 Jan 2022
[file_list, path_n] = uigetfile('.csv', 'Grab csv', 'Multiselect', 'on');
if ~iscell(file_list)
file_list = {file_list};
end
columns = cell(length(file_list),1);
for i = 1:length(file_list)
filename = file_list{i};
data_in = readmatrix([path_n, filename]);
columns{i} = data_in(:,7:27);
end
% if you want to put all the data into one matrix:
columns = cell2mat(columns);
  3 commentaires
Voss
Voss le 21 Jan 2022
That's correct: as written, they will all end up in a single matrix. But if you remove the line:
columns = cell2mat(columns);
then they'll be in a cell array where each cell contains a matrix from one file. You can access each file's data like:
columns{1}
columns{2}
columns{end}
% etc.
If all the matrices had the same size, you could put them in a 3D array instead, but a cell array of matrices of different sizes is preferable to multiple matrix variables called column_1, column_2, etc., in MATLAB. Basically, you shouldn't do the column_1, column_2 thing, and here is why: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval
lil brain
lil brain le 22 Jan 2022
Hey Benjamin, wow thanks for the insightful answer and the good directions as well. Very much appreciated! I will have a go at implenting it as a cell array then. I havent had to much experience witht he different formats and so I just kind of used what I knew. Thanks again!

Connectez-vous pour commenter.

Plus de réponses (0)

Catégories

En savoir plus sur Loops and Conditional Statements 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