How to save each loop data

Question

Chuanjung Lin 2019-10-22

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/486732-how-to-save-each-loop-data

评论： Chuanjung Lin 2019-10-30

采纳的回答： Subhadeep Koley

在 MATLAB Online 中打开

Hi all,

I have a batch file need to input to workspace for analysis, and the file type is *.csv.

Following is the code that I used, and the output file only show thw last one "P"

I hope each input file cas save as P1, P2, P3,....

May I know how to modify it ? thank you.

%% Open file dir
[filename,filedir] = uigetfile('*.csv','Multiselect','on');
path = fullfile(filedir,filename);
path = path';
file = struct('name',path); 
%% Cover struc to cell
c= struct2cell(file);
opts = delimitedTextImportOptions("NumVariables", 9);
% Specify range and delimiter
opts.DataLines = [3, Inf];
opts.Delimiter = [" ", ","];
% Specify column names and types
opts.VariableNames = ["V", "I1V", "I2V", "I3V", "I4V", "I5V", "I6V", "I7V", "I8V"];
opts.VariableTypes = ["double", "double", "double", "double", "double", "double", "double", "double", "double"];
opts.ExtraColumnsRule = "ignore";
opts.EmptyLineRule = "read";
%% Readtable Import the data
for i=1:length(file) 
    P = table2array(readtable(c{i}, opts));
end

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Stephen23 2019-10-22

编辑：Stephen23 2019-10-22

"I hope each input file cas save as P1, P2, P3,...."

Don't do that. Read this to know why:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

You should use indexing, just like the MATLAB documentation shows:

https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html

Indexing is simple, easy to debug, and very efficient (unlike what you are trying to do).

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Answer 1

Subhadeep Koley 2019-10-29

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/486732-how-to-save-each-loop-data#answer_398657

在 MATLAB Online 中打开

You defined P as a single variable, therefore it is holding only the last value of the loop. If you want to want to save each loop data to a separate variable, the following code might help you.

Just declare P as an empty cell array and access P using the indexing variable i in every loop.

%% Open file dir
[filename,filedir] = uigetfile('*.csv','Multiselect','on');
path = fullfile(filedir,filename);
path = path';
file = struct('name',path); 
%% Cover struc to cell
c= struct2cell(file);
opts = delimitedTextImportOptions("NumVariables", 9);
% Specify range and delimiter
opts.DataLines = [3, Inf];
opts.Delimiter = [" ", ","];
% Specify column names and types
opts.VariableNames = ["V", "I1V", "I2V", "I3V", "I4V", "I5V", "I6V", "I7V", "I8V"];
opts.VariableTypes = ["double", "double", "double", "double", "double", "double", "double", "double", "double"];
opts.ExtraColumnsRule = "ignore";
opts.EmptyLineRule = "read";
% Declare empty cell array P
P = {};
%% Readtable Import the data
for i=1:length(file) 
    P{i} = table2array(readtable(c{i}, opts));
end