read data from csv file & fast processing

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shaz 2012-11-7

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https://ww2.mathworks.cn/matlabcentral/answers/53017-read-data-from-csv-file-fast-processing

采纳的回答： Jan

i have a data like which is read from csv file like

10;20;2;3;45;56;87;56;988;434;10;20;2;3;45;56;87;56;988;434

i have 9lakhs of data like this what is best way to separate by ; & form a matrix

because now it is consuming to much of time

Thanks in advance

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shaz 2012-11-8

编辑：Walter Roberson 2012-11-8

在 MATLAB Online 中打开

a;b;c;d;f;g;i;p;t;r;l;e;r;y;u % Headers
10;20;2;3;4.5;56;87;56;988;434;10;20;2;3;45;56;87;56;988;434
10;20;2;3;4.5;56;87;56;988;434;10;20;2;3;45;56;87;56;988;434
10;20;2;3;45;56;87;56;988;434;10;20;2;3;45;56;87;56;988;434
....................% data
.....................% data

like wise we have 9 lakh rows(900000 rows) of data & one row of header

now how to get the headers in cell format(1st row) & rest data in matrix format

Jan 2012-11-27

@shaz: Although it looks obvious, that you neither read the comments nor care about them: Please stop using the term "lakh" without any further explanations, because it is not part of the English language such that it might confuse the readers. It is very friendly that Per explained this, but this has been your your turn actually.

Can you imagine the effects, when you do not care about questions for clarifications?

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采纳的回答

Jan 2012-11-7

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/53017-read-data-from-csv-file-fast-processing#answer_64622

编辑：Jan 2012-11-8

在 MATLAB Online 中打开

fid = fopen(FileName, 'r');
if fid == -1, error('Cannot open file!'); end
header = fgetl(fid);     % Read header line
pos    = ftell(fid);     % Store position [EDITED: fseek -> ftell]
line1  = fgetl(fid);     % first data line
data   = sscanf(line1, '%g;', Inf);
ncol   = length(data);
fmt    = repmat('%g; ', 1, ncol);
fseek(fid, pos, 'bof');  % Restore file position
data   = fscanf(fid, fmt, Inf);
data   = transpose(reshape(data, ncol, []));
fclose(fid);