how to fit different lines for scatter points from specific categorical data?

I got a table like this:

PLACE	        O18      D
Place3	-9.17	-71.68
Place2	-8.24	-61.47
Place2	-9.79	-70.24
Place3	-5.93	-62.67
Place2	-4.58	-29.3
Place1	-4.44	-26.5
Place1	-4.07	-28.4

...

which I imported like three column vectors: place, oxygen18, deuterium respectively.

plotted using

gscatter(oxygen18,deuterium,place)

and fitted a general tendency line

ft = fittype( 'poly1' );
[fit_line, gof] = fit( oxygen18, deuterium, ft);

now I would like fit a line 'oxygen18' vs 'deuterium' for each group entry in the vector 'place', i.e. 'oxigen18' vs 'deuterium' in Place1 and then for Place2 next for Place3, and so on.

How it could be achieved?.

Thanks.

Answer 1

[Adam Danz]

Easiest way is to do it in a loop.

placeUnq = unique(place); %all unique place values
fit_line_groups = cell(numel(placeUnq),1); %store results
gof_groups = fit_line_groups;  %store results

% loop through each unique place
for i = 1:numel(placeUnq)
    [fit_line_groups{i}, gof_groups{i}] = fit(oxygen18(place==placeUnq(i)), deuterium(place==placeUnq(i)), ft);
end