Values not getting printed in csv file

Hi

I have a small issue in printing the values in .csv file

Code.

for 
for 
for 
- some lines of code 
fprintf("Temperature = %3.0f\n",temp);

[fid1, msg1]   = fopen('file1.csv', 'w' );
fprintf(fid1, 'temperature');
fprintf(fid1, '%3.0f', temp );
fprintf(fid1, '\n');
fclose(fid1);
end 
end 
end

Output on the command line.

Temperature = -40
Temperature =   0
Temperature =  25
Temperature =  60
Temperature = -40
Temperature =   0
Temperature =  25
Temperature =  60
Temperature = -40
Temperature =   0
Temperature =  25
Temperature =  60

But in the CSV file i have only the last line of the output is printed.

Temperature = 60

I need to print all the values, what can be done ?

Answer 1

[Stephen23]

"Values not getting printed in csv file"

Actually they are getting printed, your code just keep overwriting them. The problem is that your code reopens the file on every loop iteration, and each time any existing file contents are simply discarded, so in the end, only the data from the last loop iteration will be in the file.

The usual solution is to open the file before the loops, and close it after the loops:

[fid, msg] = fopen('file1.csv','wt'); % this needs to be BEFORE the loops.
for 
    for 
        for 
            ...
            fprintf(fid, 'temperature %3.0f\n',temp);
        end 
    end 
end
fclose(fid); % this needs to be AFTER the loops

Alternatively you could open the file with the 'a' (append) option, but I would not recommend this as you would anyway need to fopen and fclose the file before the loop to clear any existing file data. The above solution is simpler.

[Ganesh Kini]

Thank you!!

[Ganesh Kini]

Output on the file

Temperature = -40

Temperature = 0

Temperature = 25

Temperature = 60

Temperature = -40

Temperature = 0

Temperature = 25

Temperature = 60

Temperature = -40

Temperature = 0

Temperature = 25

Temperature = 60

But i need the Output as

Temperature: -40 0 25 60 -40 0 25 60 -40 0 25 60

How can i change ?

[Stephen23]

[fid, msg] = fopen('file1.csv','wt'); % this needs to be BEFORE the loops.
fprintf(fid,'temperature');
for 
    for 
        for 
            ...
            fprintf(fid, ' %3.0f\n',temp);
        end 
    end 
end
fclose(fid); % this needs to be AFTER the loops

[Ganesh Kini]

Thank so much, I got the results

I need one help from you thats when i have

[fid1, msg1] = fopen ( 'file1.csv' , 'wt' );
fprintf (fid1, 'Temperature \ t' );
fprintf ( '\ n' );
fprintf (fid1, 'Value_n \ t' );
fprintf ( '\ n' );
fprintf (fid1, 'Value_p \ t' );

for 
    for 
        for 
            ...
            fprintf (fid1, '% 3.0f \ n' , temp);
	    fprintf (fid1, '% 1.1f \ t' , vnw);
            fprintf (fid1, '% 1.1f \ t' , vpw);
        end 
    end 
end

I get the output

Temperature VNW VPW-40 1.8 -1.5 0 1.2 -1.8 25 1.2 -1.8 60 1.2 -1.5 -40 1.2 -1.8 0 1.8 -1.2 25 0.9 -1.8 60 0.9 -1.8 -40 0.9 -1.8 0 0.9 -1.8 25 0.9 -1.8 60 0.9-1.5

[Stephen23]

If you expect each of Temperature, Value_n and Value_p to be printed on their own lines (giving three lines in total), then that is not possible using your nested-loops approach. You would have to collect the data into an array (or three vectors) and fprintf them after the loops.

Or you could simply save your data in columns (which is the standard approach), in which case it is trivial to add a new line for each loop iteration. This would be by far the simplest approach.

[Ganesh Kini]

Sorry i could not post the entire thing, since there was net issues

I should not be getting like that

in a single line, but i should get the values in 3 different lines

Temperature 40 and so on ----------

Value_n 1.8 and so on ----------

Value_p -1.5 and so on ----------

If i need to create arrays or columns ( which i am not that sure about) how can i do it? Please let me know about that too. I am really stuck with this

[Ganesh Kini]

How can i save the data in columns or in array? Probably in what way.

If you could give me an example. It would be great.

[Stephen23]

[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);

[Ganesh Kini]

Hi,

It does not work as expected

Output

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 the output in such a way

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

Could you please suggest some changes ?