MATLAB: How to enumerate an array

array enumerationMATLAB

I want a simple enumeration of the following series a=
['465465465','465465465','465465465','31546895489','31546895489','897897979','897897979', '897897979','897897979','897897979','897897979')'
in order to get
   b=(1,1,1,2,2,3,3,3,3,3,3);
I tried with
b(1:length(a))=1;
for i=2:length(a)
if isequal(a(i),a(i-1));
b(i)=b(i-1);
else
b(i)=i+1;
end
end
(but that is not the expected result)

Best Answer

Create it as a cell array, and use unique. It will give you almost what you want, however unique sorts the results, so they will not be exactly in the order you specified:
a={'465465465','465465465','465465465','31546895489','31546895489','897897979','897897979', '897897979','897897979','897897979','897897979'}';
[as,~,ic] = unique(a);
The ‘as’ vector gives you the sorted results, and ‘ic’ will give the corresponding indices in the order they appear in ‘a’.
Related Question