Import CSV file with mixed data types

Question

I'm working with MATLAB for few days and I'm having difficulties to import a CSV-file to a matrix.

My problem is that my CSV-file contains almost only Strings and some integer values, so that csvread() doesn't work. csvread() only gets along with integer values.

How can I store my strings in some kind of a 2-dimensional array to have free access to each element?

Here's a sample CSV for my needs:

04;abc;def;ghj;klm;;;;;
;;;;;Test;text;0xFF;;
;;;;;asdfhsdf;dsafdsag;0x0F0F;;

The main thing are the empty cells and the texts within the cells. As you see, the structure may vary.

Answer 1

Given the sample you posted, this simple code should do the job:

fid = fopen('file.csv','r');
C = textscan(fid, repmat('%s',1,10), 'delimiter',';', 'CollectOutput',true);
C = C{1};
fclose(fid);

Then you could format the columns according to their type. For example if the first column is all integers, we can format it as such:

C(:,1) = num2cell( str2double(C(:,1)) )

Similarly, if you wish to convert the 8th column from hex to decimals, you can use HEX2DEC:

C(:,8) = cellfun(@hex2dec, strrep(C(:,8),'0x',''), 'UniformOutput',false);

The resulting cell array looks as follows:

C = 
    [  4]    'abc'    'def'    'ghj'    'klm'    ''            ''                []    ''    ''
    [NaN]    ''       ''       ''       ''       'Test'        'text'        [ 255]    ''    ''
    [NaN]    ''       ''       ''       ''       'asdfhsdf'    'dsafdsag'    [3855]    ''    ''

Answer 2

Have you tried to use the "CSVIMPORT" function found in the file exchange? I haven't tried it myself, but it claims to handle all combinations of text and numbers.

http://www.mathworks.com/matlabcentral/fileexchange/23573-csvimport

Answer 3

I recommend looking at the dataset array.

The dataset array is a data type that ships with Statistics Toolbox. It is specifically designed to store hetrogeneous data in a single container.

The Statistics Toolbox demo page contains a couple vidoes that show some of the dataset array features. The first is titled "An Introduction to Dataset Arrays". The second is titled "An Introduction to Joins".

http://www.mathworks.com/products/statistics/demos.html