Question

In MATLAB, I’m using fprintf to print a list of numerical values under column headings, like so:

fprintf('%s %s %s %s\n', 'col1', 'col2', 'col3', 'col4')
for i = 1:length(myVar)
    fprintf('%8.4g %8.4g %8.4g %8.4g\n', myVar{i,1}, myVar{i,2}, myVar{i,3}, myVar{i,4})
end

This results in something like this:

    col1     col2     col3     col4
   123.5    234.6    345.7    456.8

However, when one of the cells is empty (e.g. myVar{i,3} == []), space is not preserved:

    col1     col2     col3     col4
   123.5    234.6     456.8

How do I preserve space in my format for a numerical value that may be empty?

Answer 1

One option is to use the functions CELLFUN and NUM2STR to change each cell to a string first, then print each cell as a string using FPRINTF:

fprintf('%8s %8s %8s %8s\n', 'col1', 'col2', 'col3', 'col4');
for i = 1:size(myVar,1)
  temp = cellfun(@(x) num2str(x,'%8.4g'),myVar(i,:),'UniformOutput',false);
  fprintf('%8s %8s %8s %8s\n',temp{:});
end

This should give you output like:

    col1     col2     col3     col4
   123.5    234.6             456.8

Notice also that I added eights to your first FPRINTF call to fix the formatting of the column labels and changed length(myVar) to size(myVar,1) since you are looping over the rows of myVar.