How to read a text file and save it as different variables

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Zee
Zee on 21 Apr 2022
Answered: Mathieu NOE on 21 Apr 2022
Hi,
I have a text file in the following format:
String line
String line
.Sample 1 0 0 0
5441.45 5454.52 5425.85 742.95
512.12 9894.21 4511.45 78921.45
.Sample 2 0 0 0
45961.45 8562.45 859.24 9453.14
845.52 6896.25 1236.45 9856.23
I have 10 such sample numbers and each sample has around 100 rows of numeric data. I want to read and save the data listed under each sample number as different variables. For example, all the data under Sample 1 0 0 0 as A, all the data under Sample 2 0 0 0 as B and so on. May I know how can I do that and which will be the best function to use.
  1 Comment
Stephen23
Stephen23 on 21 Apr 2022
"For example, all the data under Sample 1 0 0 0 as A, all the data under Sample 2 0 0 0 as B and so on."
That makes accessing your data more complex, and forces you into writing slow, complex, inefficient code:
"May I know how can I do that and which will be the best function to use."
The neat, simple, and very efficient approach is to use indexing or fieldnames.
If you upload a sample file by clicking the paperclip button then someone can help you with this.

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Accepted Answer

Mathieu NOE
Mathieu NOE on 21 Apr 2022
hello
I saved you short text from the post in a file and started some coding
nota this code contains also an alternative to readlines if you have an older release
see the results below :
data is a 2 cell array containing your 2 data :
>> data{1}
2×1 cell array
{'5441.45 5454.52 5425.85 742.95' }
{'512.12 9894.21 4511.45 78921.45'}
>> data{2}
2×1 cell array
{'45961.45 8562.45 859.24 9453.14'}
{'845.52 6896.25 1236.45 9856.23' }
code
%%%%%%%% main code %%%%%%%%%
clc
clearvars
filename = 'test.txt';
str = "Sample ";
[data] = myfunction_read(filename,str);
%%%%%%% functions %%%%%%%%%
function lines = my_readlines(filename)
% work around for earlier matlab releases (not having readlines)
lines = regexp(fileread(filename), '\r?\n', 'split');
if isempty(lines{end}); lines(end) = []; end %end of file correction
end
%%%%%%%%%%%%%%%%%%%%%%%%%
function [data] = myfunction_read(filename,str)
lines = my_readlines(filename);
% init data
count = 0;
flag = 0;
k = 0;
line_index = 1;
for ci = 1:numel(lines)
ll = lines(ci);
if contains(ll,str) %
line_index = ci;
flag = 1;
k = 0;
count = count+1;
end
if flag == 1 && ci >= line_index+1
k = k +1;
data{count}(k,:) = ll;
end
end
end

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