Unique Values based on 2 Variables

3 views (last 30 days)
This is a little complicated for me to explain, but I'll try my best. Suppose I have 2 variables, var1 and var2.
var1=[1 2 4]' %Column 1
var2(:,1)=[1 1 1 2 4 4 4]' %Column 1
var2(:,2)=[8 9 2 5 5 1 1]' %Column 2
My goal: For each value in var1, I want to refer to column 1 of var2 and find the unique number in column 2. (Forgive me, but even I find it difficult in explaining this. I will illustrate my objective)
Based on the code excerpt above,
In var1, the 1st value is 1. Compare it to var2 column 1 In var2, row 1-3 contains 1 and I wish to find the unique values in column 2.
(Answer: 8,9,2 when col1's value is 1)
(Answer: 5 when col1's value is 2)
(Answer: 5,1 when col1's value is 4)
Again, I am very sorry for this poor explanation.

Accepted Answer

Andrei Bobrov
Andrei Bobrov on 7 Jun 2013
[a,b] = ismember(var2(:,1),var1);
out = [num2cell(var1), accumarray(b(a),var2(:,2),[],@(x){unique(x)})];
  1 Comment
RDG
RDG on 7 Jun 2013
Thanks for the hint. I should be able to refine it from here.

Sign in to comment.

More Answers (1)

Image Analyst
Image Analyst on 7 Jun 2013
Why do you want to hassle with cell arrays instead of regular numerical arrays, which would be a lot simpler?
  3 Comments
Image Analyst
Image Analyst on 7 Jun 2013
I don't understand where the 8, 9, and 2 came from. If var1 = 1, this occurs in col1 of var2 in rows 1, 2, and 3. The values in rows 1, 2, and 3 of col2 of var2 are 1 & 2, not 8, 9, and 2.
RDG
RDG on 7 Jun 2013
Aye, sorrryy...I forgot to edit the question.

Sign in to comment.

Categories

Find more on Creating and Concatenating Matrices in Help Center and File Exchange

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!