Writing variables in .csv file and saving it

Hi,

I have a functionality that works perfectly fine. But the output has a set of Numeric value and text strings.

for ex: abc, 1, def,1

def,2, rfg, 1

How can i save the output in a .csv file? do i need to put all my output values of the code to a Matrix then use csvwrite() function?

Please suggest your inputs

Answer 1

[Ameer Hamza]

If you have R2019a or later, you can save the data in a cell array and use writecell()

C = {'abc', 1, 'def' 1; 'def', 2, 'rfg', 1};
writecell(C, 'test.txt')

[Ganesh Kini]

I have 15,000 entries ( as the output for the code) in that case how do i write it down ?

[Ameer Hamza]

How are you getting the output? In a variable?

[Ganesh Kini]

Actually i had posted a query earlier, but didnt get any suggestion.

Could you please check this link Example

It would be of great help

[Ameer Hamza]

It is not clear in which format are you getting the output. Is it just printed on the command window?

[Ganesh Kini]

Yes, I have specified in fprintf() in the octave code and then i will get that output in the command window.

Please let me know if you need more clarifications

[Ameer Hamza]

I think instead of printing to the command window, you can print directly to the CSV file. The actual will depend on how the values are saved inside the for-loop.

[Ganesh Kini]

Okay, could do you please suggest what can be done to this?

Do you want the printf statement that i have used?

I am not able to understand how to write it

[Ameer Hamza]

The current printf statements might not be useful. The actual issue is how all the values are saved? Are they saved in some variables?

[Ganesh Kini]

yes they are saved in different variables. each value is computed in the for-loop and then we have the value assigned to each of the variable ( both string and floating values ) and then i write everything in fprint() statement

[Ameer Hamza]

If you have all the values if a same filed inside one variable then you may try fprintf like this

fprintf('Place: ')
fprintf('%s,', place_values)

[Ganesh Kini]

Can you please let me know the full flow of the code? so that it would be easy to me to understand after the above what needs to be done and how do we write in that particular format

Is it possible to reply in this link so that it would be easy for others to understand the flow and how the code needs to be written

https://de.mathworks.com/matlabcentral/answers/542873-how-to-write-the-output-of-the-code-to-csv-format-and-save-the-file?s_tid=prof_contriblnk

[Ameer Hamza]

I meant that you can do it for each line. For example,

fprintf('Place: ')
fprintf('%f,', place_values)
fprintf('\n');
fprintf('Repeated Place: t,')
fprintf('f,', ones(1,size(place_values)))
fprintf('\n');
fprintf('Temperature: ')
fprintf('%f,', temperature_values)
fprintf('\n');
..
..
% similarly for other fields.

[Ganesh Kini]

Okay i will try and how do i save it in .csv file ?

Please suggest me the code for that

[Ameer Hamza]

fprintf() can write to a file as well

fid = fopen('filename.csv');
fprintf(fid, 'Place: ')
fprintf(fid, '%f,', place_values)
fprintf(fid, '\n');
fprintf(fid, 'Repeated Place: t,')
fprintf(fid, 'f,', ones(1,size(place_values)))
fprintf(fid, '\n');
fprintf(fid, 'Temperature: ')
fprintf(fid, '%f,', temperature_values)
fprintf(fid, '\n');
..
..
% similarly for other fields.
fclose(fid)

[Ganesh Kini]

Okay i will try.

Is it possible to write using csvwrite function?

i wanted to know about that

[Ameer Hamza]

csvwrite is used to write a numeric matrix. It is not useful here.

[Ganesh Kini]

Hi Ameer,

When i try to run this code

[fid1, msg1]   = fopen('file.csv');
fprintf(fid1, 'temperature ');
fprintf(fid, '%3.0f,', temp );
fprintf(fid, '\n');
fclose(fid);

Error

>> msg1
  msg1 = No such file or directory
>> fid1
  fid1 = -1
  

I should create a csv file and then enter the values. How can we do it ?

[Ameer Hamza]

You need to specify that you want to open the file for writing

[fid1, msg1]   = fopen('file.csv', 'w');

[Ganesh Kini]

Hi I was running this code

[fid, msg] = fopen ( 'file1.csv' , 'wt' );
assert (fid> = 3, msg)
fprintf (fid, '% s \ t% s \ t% s \ n' , 'Temperature' , 'Value_n' , 'Value_p' );
for 
    for 
        for 
            ...
            fprintf (fid, '% 3.0f \ t% 1.1f \ t% 1.1f \ n' , temp, vnw, vpw);
        end 
    end 
end
fclose (fid);

Output of the code

Temperature  Value_n Value_p ,-40 0.2 0.1 20 0.1 0.4 120 0.5 4.5

where as i should get

Temperature, -40 20 120
Value_n, 0.2 0.1 0.5
Value_p, 0.1 0.4 4.5

How can i change to get the above output?

[Ameer Hamza]

Try to write it seperately

[fid, msg] = fopen ( 'file1.csv' , 'wt' );
assert (fid> = 3, msg)
fprintf (fid, '% s \t' , 'Temperature');
for 
    for 
        for 
            ...
            fprintf (fid, '% 3.0f \t' , temp);
        end 
    end 
end
fprintf (fid, '\n' , temp);
for 
    for 
        for 
            ...
            fprintf (fid, '% 3.0f \t' , vnw);
        end 
    end 
end
fprintf (fid, '\n' , temp);
% same for vpw
fclose (fid);

[Ganesh Kini]

Yes that would work but i can not use for loop like that, because i have 10 variables

10*3 -- 30 for loops will not be feasible.

Is there any alternate way?

[Ameer Hamza]

Something like this

[fid, msg] = fopen ( 'file1.csv' , 'wt' );
assert (fid> = 3, msg)
labels = {'Temperature', 'Value_n', 'Value_p'};
vars = {temp, vnw, vpw}

for i=1:numel(labels)
    fprintf (fid, '% s \t' , labels{i});
    for 
        for 
            for 
                ...
                fprintf (fid, '% 3.0f \t' , vars{i});
            end 
        end 
    end
    fprintf (fid, '\n' , temp);
end
fclose (fid);

[Ganesh Kini]

Hi Ameer,

Tried your method, it didn't work as expected

Temperature t 60 60 60 60 60 60 60 60 60 60 60 60

Value_n t 1 1 1 1 1 1 1 1 1 1 1 1

Value_p t -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2

Could you please tell me where i can change this?

The value needs to change after one complete execution, but it is not doing that

[Ganesh Kini]

size(backend_full)

Output 
  ans =
     12    7

But when i write the above code for repeated values

fprintf (fid2, '\nEnable,t,');

fprintf (fid2, 'f,', ones(1,size(backend_full)));

Output on the csv file
  
  Enable,t,f, 

Please let me know

[Ameer Hamza]

Are all the variables calculated before this line?

vars = {temp, vnw, vpw}

or are they calculated inside for-loop?