changing header to csv using writetable

I have a 2D array like this: dates and data

19790101 7839.4 29.4 17.3 1.6 51.8 13.8 5.2

19790102 8046.4 30.1 17.5 0.1 45.2 16.2 4.9

19790103 9018.2 27.6 13.5 0 40.9 14.3 5.2

19790104 5359.4 21.8 14.4 0.2 61.5 8 4.9

19790105 8145.9 26.4 13.6 0.7 52.2 11.2 3.8

...

I saved it into a csv file as

T = array2table(d);

T.Properties.VariableNames(1:8) = {'a','b','c','d','e','f','g','h'};

writetable(T,'myfile.csv','WriteVariableNames',0)

Since writetable doesn't allow headers using ( ) or other characters, I used 'a' 'b'...

What I need id to change that arbitrary header for another one like

Date Rad(Wm-2) Tmx(C) Tmn(C) Pre(mm) Rhd(%) Vpd(hPa) Wp10(ms-1)

I didn't do this directly using csvwrite because it writes the output of the first column in scientific notation

Thank you

Answer 1

[Star Strider]

In R2016b, the variable names must be valid MATLAB variable names. (That changed in R2020a, so what you want to do would be permitted.)

The other problem you are having is that the dates in column #1 need to be a datetime array.

This does everything except use the variable names you want:

M = [19790101  7839.4  29.4  17.3  1.6  51.8  13.8  5.2 
     19790102  8046.4  30.1  17.5  0.1  45.2  16.2  4.9
     19790103  9018.2  27.6  13.5  0  40.9  14.3  5.2
     19790104  5359.4  21.8  14.4  0.2  61.5  8  4.9
     19790105  8145.9  26.4  13.6  0.7  52.2  11.2  3.8 ];

T1 = array2table(M);
DT = datetime(num2str(M(:,1)), 'InputFormat','yyyyMMdd');
T1.M1 = DT

producing:

T1 =

  5×8 table

        M1           M2       M3      M4     M5      M6      M7     M8 
    ___________    ______    ____    ____    ___    ____    ____    ___

    01-Jan-1979    7839.4    29.4    17.3    1.6    51.8    13.8    5.2
    02-Jan-1979    8046.4    30.1    17.5    0.1    45.2    16.2    4.9
    03-Jan-1979    9018.2    27.6    13.5      0    40.9    14.3    5.2
    04-Jan-1979    5359.4    21.8    14.4    0.2    61.5       8    4.9
    05-Jan-1979    8145.9    26.4    13.6    0.7    52.2    11.2    3.8

Change the variable names to versions of what you have that will work in R2016a. Even if you change them to what you want in the file, they will be changed to valid MATLAB variable names when you import it. Your only option is to upgrade to R2020a or later to use the variable names you want to use.

You can then use writetable with ‘T1’ (or whatever you wish to name it in your code).

EDIT — (16 Nov 2020 at 20:40)

To have the datetime column in the original format, add the 'Format' name-value pair to the datetime call in the ‘DT’ assignment:

DT = datetime(num2str(M(:,1)), 'InputFormat','yyyyMMdd', 'Format','yyyyMMdd');

The rest of the code is unchanged.

       M1         M2       M3      M4     M5      M6      M7     M8 
    ________    ______    ____    ____    ___    ____    ____    ___

    19790101    7839.4    29.4    17.3    1.6    51.8    13.8    5.2
    19790102    8046.4    30.1    17.5    0.1    45.2    16.2    4.9
    19790103    9018.2    27.6    13.5      0    40.9    14.3    5.2
    19790104    5359.4    21.8    14.4    0.2    61.5       8    4.9
    19790105    8145.9    26.4    13.6    0.7    52.2    11.2    3.8

.

[Simon Lind]

thank you very much for your help

[Star Strider]

My pleasure!

Answer 2

[Ameer Hamza]

Try something like this

 T = [ ...
 19790101  7839.4  29.4  17.3  1.6  51.8  13.8  5.2 
 19790102  8046.4  30.1  17.5  0.1  45.2  16.2  4.9 
 19790103  9018.2  27.6  13.5  0  40.9  14.3  5.2 
 19790104  5359.4  21.8  14.4  0.2  61.5  8  4.9 
 19790105  8145.9  26.4  13.6  0.7  52.2  11.2  3.8 ];

fid = fopen('myfile.csv', 'w');
fprintf(fid, 'Date  Rad(Wm-2)  Tmx(C)  Tmn(C)  Pre(mm)  Rhd(%%)  Vpd(hPa)  Wp10(ms-1)\n');
fclose(fid);

writematrix(T, 'myfile.csv', 'WriteMode', 'append')

[Simon Lind]

Thank you. I forgot to mention that I'm using R2016b version

any alternative to writematrix?

[Ameer Hamza]

Try this

T = [ ...
19790101  7839.4  29.4  17.3  1.6  51.8  13.8  5.2 
19790102  8046.4  30.1  17.5  0.1  45.2  16.2  4.9 
19790103  9018.2  27.6  13.5  0  40.9  14.3  5.2 
19790104  5359.4  21.8  14.4  0.2  61.5  8  4.9 
19790105  8145.9  26.4  13.6  0.7  52.2  11.2  3.8 ];

fid = fopen('myfile.csv', 'w');
fprintf(fid, 'Date  Rad(Wm-2)  Tmx(C)  Tmn(C)  Pre(mm)  Rhd(%%)  Vpd(hPa)  Wp10(ms-1)\n');
fclose(fid);

dlmwrite('myfile.csv', T, '-append')

[Simon Lind]

thank you. I tried this option but dlmwrite writes the first column in scientific notation

1.98E+07

instead of

19790101

[Ameer Hamza]

You may try fprintf with custom formatting

T = [ ...
19790101  7839.4  29.4  17.3  1.6  51.8  13.8  5.2 
19790102  8046.4  30.1  17.5  0.1  45.2  16.2  4.9 
19790103  9018.2  27.6  13.5  0  40.9  14.3  5.2 
19790104  5359.4  21.8  14.4  0.2  61.5  8  4.9 
19790105  8145.9  26.4  13.6  0.7  52.2  11.2  3.8 ];

fid = fopen('myfile.csv', 'w');
fprintf(fid, 'Date  Rad(Wm-2)  Tmx(C)  Tmn(C)  Pre(mm)  Rhd(%%)  Vpd(hPa)  Wp10(ms-1)\n');
fprintf(fid, '%8.0f %4.1f %2.1f %2.1f %2.1f %2.1f %2.1f %2.1f \n', T.');
fclose(fid);

[Simon Lind]

thank you very much for your help