# How to conditionally merge rows in a table

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Blue on 8 Jan 2021
Edited: Stephen Cobeldick on 8 Jan 2021
Hi,
I have a quick question - I have the following table T and I would like to merge the rows where the values of the variables lat, lon and id are identical and where only the values of the key variable are different. The desired output is shown.
lat = [45.67, 45.67, 56.89, 78.61]';
lon = [-66.45, -66.45, -65, -67]';
id = [202, 202, 201, 200]';
key = {'A', 'B', 'C', 'C'}';
T = table(lat, lon, id, key)
[C, ia, ic] = unique(T(:, 1:3),'rows')
% desired output:
lat = [45.67, 56.89, 78.61]';
lon = [-66.45, -65, -67]';
id = [202, 201, 200]';
key = {'A, B', 'C', 'C'}';
desired_output = table(lat, lon, id, key)
Thank you,

Stephen Cobeldick on 8 Jan 2021
Edited: Stephen Cobeldick on 8 Jan 2021
lat = [45.67, 45.67, 56.89, 78.61]';
lon = [-66.45, -66.45, -65, -67]';
id = [202, 202, 201, 200]';
key = {'A', 'B', 'C', 'C'}';
T = table(lat, lon, id, key)
T = 4x4 table
lat lon id key _____ ______ ___ _____ 45.67 -66.45 202 {'A'} 45.67 -66.45 202 {'B'} 56.89 -65 201 {'C'} 78.61 -67 200 {'C'}
[C, ia, ic] = unique(T(:, 1:3),'rows');
C.key = splitapply(@(s)join(s,', '),T.key,ic)
C = 3x4 table
lat lon id key _____ ______ ___ ________ 45.67 -66.45 202 {'A, B'} 56.89 -65 201 {'C' } 78.61 -67 200 {'C' }