How to change duplicate values, so that every value is unique

Hello everyone,

At this moment i am stuck with the following problem. I want to change the values of duplicate values, so every value is unique. While it is not allowed to change the position of these numbers in the matrix. Below is the starting matrix.

a = [10 20 20 30 20 30 40]';

And the desired output would be this:

b = [10 20 20.01 30 20.02 30.01 40]';

Thanks in advance!

[David Goodmanson]

Hi Richard, Take a look at the 'unique' function. After you have the unique values you can see how many times each one occurs and change the extra ones.

Answer 1

[Walter Roberson]

[uvals, ~, uidx] = unique(a, 'stable');
b = a;    %mostly to copy the class and size
for K = 1 : length(uvals)
  mask = uidx == K;
  b(mask) = uvals(K) + (0 : nnz(mask) - 1) * 0.01;
end

[Richard Wolvers]

Thanks!

Answer 2

[Andrei Bobrov]

a = [10 20 20 30 20 30 40]';
[~,ii] = sort(a);
[~,~,c] = unique(a);
jj = cell2mat(accumarray(c,.1*ones(numel(a),1),[],@(x){cumsum(x)}));
out = jj(ii)-.1 + a;

or

a = [10 20 20 30 20 30 40]';
t = a == unique(a)'; % for MATLAB <= R2016a: t = bsxfun(@eq,a(:),unique(a)');
out = sum(cumsum(.1*t).*t,2)-.1 + a;