MATLAB:LaTeX Table Writer

Sometimes you will need to take data from a MATLAB script or function and present it using a LaTeX table. Rather than hand-code all the numbers, you may want to write a MATLAB loop to take care of producing the LaTeX code.

Create the Matrices

Probably the easiest way to create the table is to make sure all the information you want is stored in 1-D matrices (either columns or rows). Then you can just run a for loop with an indexing variable to pull out the appropriate values. For example if you want a table with temperatures in different units, you could start with:

TC = [-273.15 -40 0 100]';
TK = TC + 273.15;
TF = (TC+40)*9/5-40;
TR = TF + 459.67;

Generate LaTeX Code

Keep in mind for LaTeX tables, the entries are separated by & and the rows are terminated with \\. In MATLAB, to print a \, you must actually use the backslash command, which is \\. To get MATLAB to go to the next line, you need to use the \n command.

The following loop might be used to create the main parts of the LaTeX table for the matrices above:

for k=1:length(TC)
    fprintf('%8.2f & %8.2f & %8.2f & %8.2f \\\\ \n', TC(k), TK(k), TF(k), TR(k))
end

The output from this code is:

-273.15 &     0.00 &  -459.67 &     0.00 \\
 -40.00 &   233.15 &   -40.00 &   419.67 \\
   0.00 &   273.15 &    32.00 &   491.67 \\
 100.00 &   373.15 &   212.00 &   671.67 \\

Extra Code

Horizontal Lines

If you want horizontal lines between rows, LaTeX needs the \hline command after the double-slashes. Keeping in mind that MATLAB needs to \ two produce a \, you can write

for k=1:length(TC)
    fprintf('%8.2f & %8.2f & %8.2f & %8.2f \\\\ \\hline  \n', TC(k), TK(k), TF(k), TR(k))
end

to get:

-273.15 &     0.00 &  -459.67 &     0.00 \\ \hline
 -40.00 &   233.15 &   -40.00 &   419.67 \\ \hline
   0.00 &   273.15 &    32.00 &   491.67 \\ \hline
 100.00 &   373.15 &   212.00 &   671.67 \\ \hline

Saving to a File

If you want to save your table to a file, you can use the fopen and fclose command with file handles to tell fprintf to produce a file instead of printing to the screen. For the example, above, just a few changes will save the table data to a text file instead of printing it to the screen:

FID = fopen('file.tex', 'w')
for k=1:size(MainMat, 1)
    fprintf(FID, '%8.2f & %8.2f & %8.2f & %8.2f \\\\ \n', TC(k), TK(k), TF(k), TR(k))
end
fclose(FID)

Complete Example

If you want MATLAB to write everything for the table, you can add lines to write the \begin{tabular} and all the other infrastructure required for a table. The convenience there is that you would only need to tell your main LaTeX file to input the subordinate file to place the table. Specifically, you could write the following MATLAB code:

FID = fopen('file.tex', 'w');
fprintf(FID, '\\begin{tabular}{|rrrr|}\\hline \n');
fprintf(FID, 'T ($^{\\circ}$C) & T (K) & T ($^{\\circ}$F) & T ($^{\\circ}$R)\\\\ \\hline \n');
for k=1:length(TC)
    fprintf(FID, '%8.2f & %8.2f & %8.2f & %8.2f \\\\ ', TC(k), TK(k), TF(k), TR(k));
    if k==length(TC)
        fprintf(FID, '\\hline ');
    end
    fprintf(FID, '\n');
end

fprintf(FID, '\\end{tabular}\n');
fclose(FID);

will create the code:

\begin{tabular}{|rrrr|}\hline 
T ($^{\circ}$C) & T (K) & T ($^{\circ}$F) & T ($^{\circ}$R)\\ \hline 
 -273.15 &     0.00 &  -459.67 &     0.00 \\ 
  -40.00 &   233.15 &   -40.00 &   419.67 \\ 
    0.00 &   273.15 &    32.00 &   491.67 \\ 
  100.00 &   373.15 &   212.00 &   671.67 \\ \hline 
\end{tabular}

The code to include it in a LaTeX document is:

\begin{center}
\input{file.tex}
\end{center}

When processed, it produces the following table:

\( \begin{array}{|rrrr|}\hline \mbox{T (}^{\circ}\mbox{C)} & \mbox{T (K)} & \mbox{T (}^{\circ}\mbox{F)} & \mbox{T (}^{\circ}\mbox{R)}\\ \hline -273.15 & 0.00 & -459.67 & 0.00 \\ -40.00 & 233.15 & -40.00 & 419.67 \\ 0.00 & 273.15 & 32.00 & 491.67 \\ 100.00 & 373.15 & 212.00 & 671.67 \\ \hline \end{array} \)

Note that if you specifically want all the numbers in the table to be the same width, you may need to specify that the table should be in typewriter mode. That is:

\begin{center}
{\tt
\input{file.tex}
}
\end{center}

Testing On Screen

Note that sometimes you will want to see your file print to the screen before printing it to a file. A file identifier of 1 means to go to the screen. If you want to look at your prints to the screen first, change the first line above to:

%FID = fopen('file.tex', 'w');
FID = 1

You may also want to comment out the fclose line, as it cannot close the screen!

Questions

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