Your for loop is fine. But there's no such thing as elements 0 or 0.1 of an array in MATLAB (the first element of an array in MATLAB is element 1), so your attempt to assign into those elements in y_ord will fail.
You could create that vector and iterate over the elements of that vector:
edges = 0:0.01:1;
for whichedge = 1:numel(edges)
ii = edges(whichedge)
y_ord(whichedge) = someFunctionOfii;
end
Though now that I look at your code, you can probably just use groupsummary. The "Group Operations with Vector Data" example on that page is closest to what you're trying to do, only you'd specify numbers (the edges of your bins) instead of 'dayname' to define the bins and 'max' or @max as the summary function instead of 'mean'.
