Textscan doesn't work in reading csv files

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BR 2017-10-27

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https://ww2.mathworks.cn/matlabcentral/answers/363651-textscan-doesn-t-work-in-reading-csv-files

评论： Cam Salzberger 2017-10-27

I have a very large csv file with strings and Numeric values all together in it. The number of rows in the file exceeds more than 2 million. So, I can't even open in Excel. I tried using the following format

fileID = fopen('IBM.FullDepth.20140128.csv');
C = textscan(fileID,'%f %f %f %s %s %f %f %s %s');
fclose(fileID);

but the returned value of cell 'C' is empty. And I can't upload the file, since the size is too big please help.

Thanks

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Answer 1

Star Strider 2017-10-27

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https://ww2.mathworks.cn/matlabcentral/answers/363651-textscan-doesn-t-work-in-reading-csv-files#answer_288129

If you have R2013b or later, use the readtable (link) function.

Otherwise, see if you can read it with the xlsread (link) function.

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Star Strider 2017-10-27

As always, my pleasure!

The readtable function uses whatever it needs to import your data. To the best of my knowledge, neither readtable nor xlsread require (or even accept) format descriptors.

Cam Salzberger 2017-10-27

readtable will accept an optional 'Format' argument, but it is not necessary.

xlsread is for use on Microsoft Excel files. A CSV file is simply a text file with (most-commonly) comma-separated values. It is not an Excel file, despite Excel being a very common program used to open that type of file. xlsread will not work for CSV files when in basic mode at least (i.e. on non-Windows platforms, or if Excel is not installed).

csvread and dlmread are options for CSV files, but only work for numeric-data.

If you are reading a CSV with non-numeric data file pre-R2013b, you can always use fileread to just get the text at once, then parse it separately. Or do low-level file reading, as you tried with textscan.

-Cam

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