MATLAB: How to ignore additional columns when reading a file using textscan

textscantimestamp

I want to extract the 3rd column which contains the time data. I have managed to do it using

if true
f = fopen ('trial1.csv');
C = textscan(f,'%n %n %s','Delimiter',',','HeaderLines', 1)
TimeStamp=C{3}(1)'
 DateVector = datevec(TimeStamp)
 fclose(f);    
end

In the future, I can have additional 50(for eg) new columns. I want to know is there way in matlab such that i do not define these additonal columns which can comprise of string, floating numbers etc. My textscan will become so big! Any other way of extracting the time values in column 3?

2. Secondly, why is my timeStamp value not including the seconds? It is only including until the minutes!

Please find attached the trial1.csv file

Best Answer

just type doc textscan and you can find this there. So you need to add the * after the % sign for data that you do not want to read in

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FileID = fopen('data.txt','r');
C = textscan(FileID,'%s %f %f','HeaderLines',1,'Delimiter',',');
fclose(FileID);
C{1}
C{2}
C{3}

MATLAB: How to extract a portion of a CSV file using MATLAB

The following code demonstrates how this functionality can be achieved:

function test
% Set parameters.
inputFile = 'input.csv';
outputFile = 'output.csv';
totalColumns = 4;
rowBegin = 2;
rowEnd = 3;
columnBegin = 2;
columnEnd = 3;
delimiter = ';';
% Call function.
extractdata(inputFile, outputFile, totalColumns, rowBegin, rowEnd, columnBegin, columnEnd, delimiter);
% Function definition.
function extractdata(inputFile, outputFile, totalColumns, rowBegin, rowEnd, columnBegin, columnEnd, delimiter)
% Open input file.
fid = fopen(inputFile, 'r');
% Get header in one line and extract .
headerLines = fgetl(fid);
% Remove trailing delimiter.
if strcmp(headerLines(end), delimiter)
      headerLines = headerLines(1:end-1);
end
% Extract requested portion of the header.
headerLines = textscan(headerLines, [repmat('%*s', 1, columnBegin - 1) repmat('%s', 1, columnEnd - columnBegin + 1) repmat('%*s', 1, totalColumns - columnEnd)], 'Delimiter', delimiter, 'CollectOutput', 1);
headerLines = headerLines{1,1};
% Get integer (%d) data, extracting the requested portion.
% web([docroot '/techdoc/ref/textscan.html'])
C = textscan(fid, [repmat('%*d', 1, columnBegin - 1) repmat('%d', 1, columnEnd - columnBegin + 1) repmat('%*d', 1, totalColumns - columnEnd)], rowEnd, 'Delimiter', delimiter, 'CollectOutput', 1);
% Close input file.
fclose(fid);
% Extract rows.
C = C{1,1};
C = C(rowBegin:rowEnd,:);
% Write extracted column headers in new file.
headerLines = cellfun(@(x)sprintf(['%s' delimiter],x), headerLines, 'UniformOutput', false);
headerLines = cell2mat(headerLines);
headerLines = [headerLines(1:end-1) '\n']; % Remove trailing delimiter and append newline.
fid = fopen(outputFile, 'wt');
fprintf(fid, headerLines);
fclose(fid);
% Append numeric data.
dlmwrite(outputFile, C, '-append', 'delimiter', delimiter, 'precision', '%d', 'newline', 'pc');

Best Answer

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