Saving Numeric Matrix and Cell Data to CSV File in Matlab

Question

in Matlab I have one 100X4000 mat which contains doubles and I have a 100X1 cell of chars. now the problem is how can I write all together in a CSV file. Matlab doesn't let me to do that. a shorter example is like this: first mat

second cell:

apple
banana
cherry
peach
other

the expected result (A) is:

0   1   2 apple
0   0   0 banana
0   5   3 cherry
9   0   7 peach
0   4   0 other

final goal is to do this:

csvwrite('dataLabels.csv',A);

Possible duplicate: stackoverflow.com/questions/14551153/… — brodoll
– brodoll, Commented Apr 24, 2015 at 0:18
@brodroll That answer is very inefficient. Also that's only half the question. This one has a numeric matrix too. — krisdestruction
– krisdestruction, Commented Apr 24, 2015 at 1:49
OP can you verify if my answer works for you and kindly accept if it's incorrect — krisdestruction
– krisdestruction, Commented Apr 24, 2015 at 1:57
@krisdestruction The one in the link provided requires writing numeric and char data to a csv, so they are the same in this aspect. The only difference is that here the data is in two different "containers" instead of a single cell array. — brodoll
– brodoll, Commented Apr 24, 2015 at 2:02
Yes so the problem exists from the OP's question of how to convert it to a numeric. The answer in the linked post is still pretty inefficient IMHO. — krisdestruction
– krisdestruction, Commented Apr 24, 2015 at 2:04

krisdestruction · Accepted Answer · 2015-04-24 01:43:58Z

1

The code is as simple as follows:

% Toy Example Data
B = [0 1 2; 0 0 0; 0 5 3; 9 0 7; 0 4 0];
C = { 'apple' 'banana' 'cherry' 'peach' 'other' }';

B = num2str(B,'%i   %i   %i');
dlmwrite( 'dataLabels.csv', [B repmat( char(' '), length(C), 1 ) char( C{:} )], '' );

So what you want to do is change your matrix B into a char with your desired spacing. That's what the num2str function does with those parameters. Then you can use dlmwrite to delimit with no spacing. The code char( C{:} ) simply converts the cell into a char.

The code repmat( char(' '), length(C), 1 ) is just to put a space in between the matrix B and char cell C. Results

0   1   2 apple 
0   0   0 banana
0   5   3 cherry
9   0   7 peach 
0   4   0 other

edited Apr 24, 2015 at 1:43

answered Apr 24, 2015 at 1:36

krisdestruction

1,9601 gold badge10 silver badges20 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

brodoll Over a year ago

You made me curious about how much more efficient this solution is! But I can already tell this is indeed more efficient since you eliminated the need of 2 for loops. Nice one +1

krisdestruction Over a year ago

Thank you :) The solution you linked did indeed work for both numerics and cells, but as you can see, everyone resorts to the double loop and this is a very vectorized solution. I hate clunky code XD

Madken · Accepted Answer · 2015-04-24 00:31:02Z

0

You can use fopen(filepath, w) and fprintf(fileId, data) to write several matrices as strings in a csv file.

Example:

function createCSV(name, data1, data2)
fileId = fopen(path/to/file.csv, 'w');
[x, y] = size(data);

for i = 1:x
    for j = 1:y
        fprintf(fileId, num2str(data(x, y)));
        fprintf(fileId, ',');
    end
    fprintf(fileId, num2str(data2(x)));
    fprintf(fileId, '\n');
end

end

fopen, fprintf

answered Apr 24, 2015 at 0:31

Madken

113 bronze badges

1 Comment

krisdestruction Over a year ago

Your code is very inefficient due to the double loop :/

Collectives™ on Stack Overflow

Saving Numeric Matrix and Cell Data to CSV File in Matlab

2 Answers 2

2 Comments

fopen, fprintf

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

fopen, fprintf

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related