# How to count the number of unique elements by group in a table

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Blue on 8 Aug 2019
Answered: Blue on 8 Aug 2019
Hi,
How can I count the number of unique elements by group in a table and save the answer in a vector ?
% Create table
name = {'A', 'A', 'A', 'B', 'B', 'B', 'C', 'C', 'C'}.';
type = {'AA', 'BB', 'CC', 'BB', 'BB', 'BB', 'AA', 'CC', 'CC'}.';
t = table(name, type);
For example, in the table here the number of unique 'type' per 'name' would yield 3, 1, 2 (i.e. 3 'unique 'types' for name A, 1 'unique 'types' for name B, and 2 'unique 'types' for name C,)
Thank you,

Blue on 8 Aug 2019
name = {'A', 'A', 'A', 'B', 'B', 'B', 'C', 'C', 'C'}.';
type = {'AA', 'BB', 'CC', 'BB', 'BB', 'BB', 'AA', 'CC', 'CC'}.';
t = table(name, type);
n_type = rowfun(@(v) numel(unique(v)), t, 'GroupingVariables', 'name', 'InputVariables', 'type')

KALYAN ACHARJYA on 8 Aug 2019
Edited: KALYAN ACHARJYA on 8 Aug 2019
name = {'A', 'A', 'A', 'B', 'B', 'B', 'C', 'C', 'C'}.';
type = {'AA', 'BB', 'CC', 'BB', 'BB', 'BB', 'AA', 'CC', 'CC'}.';
t = table(unique(name), unique(type))
Command Window:
t =
3×2 table
Var1 Var2
_ ____
'A' 'AA'
'B' 'BB'
'C' 'CC'
Unique Elements
>> H=height(t)
H =
3

#### 1 Comment

Blue on 8 Aug 2019
Thank you kindly for your answer but it doesnt quite do what I want. I need a count of the unique elements per group, in this case 3,1,2.