How can I export only specific data from a text file to a matrix?
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I'm need to import only the numeric data of the attached .txt file into a 9x8 matrix and I'm not sure how to do this. Any help is greatly appreciated!
3 Kommentare
dpb
am 24 Jul. 2019
What Adam said...
But, it's generally simpler to read what section of a file contains the info of interest and then just throw out what you don't need than it is to specifically hunt and peck through a file reading a bit here and there.
But, it certainly isn't at all clear what you want to retrieve from this file given the question wording...
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Jan
am 25 Jul. 2019
Bearbeitet: Jan
am 26 Jul. 2019
With some guessing, that you want the part behind ':Solar_Radio_Flux:' :
Key = ':Solar_Radio_Flux:';
Str = fileread(FileName);
C = strsplit(Str, newline);
index = find(strncmp(C, Key, numel(Key)));
Block = C(index+3:index+11);
BlockStr = sprintf('%s ', Block{:}); % Horizontal concatenation
% Data = sscanf(BlockStr, '%g ', [9, 8]); [EDITED:]
Data = sscanf(BlockStr, '%g ', [8, 9])'; % Thanks Adam
This can be expanded e.g. to read the 2 header lines also or to accept any block of numbers until the next comment line.
2 Kommentare
Adam Danz
am 25 Jul. 2019
That last line should be
Data = sscanf(BlockStr, '%g ', [8, 9])';
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Adam Danz
am 25 Jul. 2019
rows = 11:19; % NUMERIC ROWS IN TEXT FILE TO IMPORT
nColumns = 8; % NUMBER OF COLUMNS OF TEXT
file = 'Testdata.txt'; % THE FULL PATH WOULD BE BETTER
opts = delimitedTextImportOptions('NumVariables',nColumns,'DataLines',rows([1,end]),'Delimiter', " ", ...
'VariableTypes',repmat({'double'},1,nColumns),'ConsecutiveDelimitersRule','join',...
'LeadingDelimitersRule','ignore');
Testdata = readtable(file, opts);
Testdata = table2array(Testdata);
Result
Testdata =
245 14 12 11 -1 -1 -1 -1
410 25 28 26 -1 -1 -1 -1
610 34 -1 34 -1 -1 -1 -1
1415 45 49 55 -1 -1 -1 -1
2695 104 -1 68 -1 -1 -1 -1
2800 -1 -1 -1 68 68 -1 -1
4995 107 113 126 -1 -1 -1 -1
8800 223 230 218 -1 -1 -1 -1
15400 519 549 496 -1 -1 -1 -1
5 Kommentare
Adam Danz
am 25 Jul. 2019
Bearbeitet: Adam Danz
am 25 Jul. 2019
@madhan ravi, it's the same. That's the only line in the table2array function. Matlab's import data tool uses table2array() which is why I ended up using it, too. But I agree that Testdata{:,:} is more direct.
Jeremy Hughes
am 25 Jul. 2019
Or if you have R2019a
Testdata = readtable(file, opts);
Testdata = table2array(Testdata);
can just be
A = readmatrix(file,opts)
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