I would do it like this:
First create a function to create a matrix, given column vectors of ids, ans, and steps for a single subject (I'm using more meaningful variable names. You certainly shouldn't call a variable ans):
%saved in its own m file:
function m = makeMatrix(rows, values, ncols)
m = zeros(102, sum(ncols)); %create matrix full of zeros
m(sub2ind(size(m), repelem(rows, ncols), (1:sum(ncols))')) = repelem(values, ncols);
end
%demo table:
t = array2table([9 1 10 -1 15
9 2 8 1 20
9 3 10 -1 10
10 1 5 1 5
10 2 6 -1 8], ...
'VariableNames', {'Subject', 'Number', 'ID', 'ANS', 'Steps'});
%apply function
c = rowfun(@makeMatrix, t, 'GroupingVariables', 'Subject', 'InputVariables', {'ID', 'ANS', 'Steps'}, 'OutputFormat', 'cell');
You can then transforim that output cell array into a structure:
s = cell2struct(c, compose('Subject%d', unique(t.Subject)), 1)
