How can I extract a portion of a CSV file using MATLAB?

I have a CSV file with the following format:

 Header 1;Header 2;Header 3;Header 4

 1;2;3;4

 5;6;7;8

 9;10;11;12

 13;14;15;16

I would like to extract the header and part of the data, for example as follows:

 Header 2;Header 3

 6;7

 10;11

Answer 1

[MathWorks Support Team]

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');