Track changes in a cell array with string elements in Matlab - arrays

Question

I have a cell array with 5 columns and about 5000 rows with string elements. E.g.:
1997 Charles House Materials Chemicals
The years go from 1997 to 2013 and you find repetitions while the years pass by. What I would like to get is a new cell array with the cases in which the combination of the second and third column change. E.g. original cell array:
1997 Charles House Materials Chemicals %initial
1997 Rita Office Financial Bank %initial
1998 Rita Office Financial Bank %no change
1999 Charles House Materials Chemicals %no change
2000 Charles Office Materials Chemicals %change in the 2nd column
2001 Charles Office Materials Chemicals %no change
2003 Rita Star Financial Bank %change in the 2nd column
2005 Charles Castle Materials Chemicals %change in the 2nd column
2010 Rita Moon Financial Bank %change in the 2nd column
I would like for my new array to give me the first/original row and the cases in which you
observe a change. E.g. output:
1997 Charles House Materials Chemicals
1997 Rita Office Financial Bank
2000 Charles Office Materials Chemicals
2003 Rita Star Financial Bank
2005 Charles Castle Materials Chemicals
2010 Rita Moon Financial Bank
My problem is mainly related to the fact I am dealing with strings. If one could help me I would appreciate. Thanks a lot for your availability.

Answer 1

Code
%// Assuming input_cellarr is the input cell array
[~,~,col2id] = unique(input_cellarr(:,2),'stable')
[~,~,col3id] = unique(input_cellarr(:,3),'stable')
[~,unqrows] = unique([col2id col3id],'rows','stable')
out = input_cellarr(unqrows,:) %// Desired output

Answer 2

First of all, I filtered out the first column because the year does not matter. Then, you have to compare the previous with the next line. This is done using X(1:end-1,2:end) and X(2:end,2:end)). Only if row wise equal, nothing has change.
changes=all(strcmpi(X(1:end-1,2:end),X(2:end,2:end)),2)
%at this point we are missing the first line
changes=[true;changes]
%finally use logical indexing to select the relevant data.
result=X(changes,:);