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How to find the location of a minimum value in cell array?

Asked by Matt Learner

Matt Learner (view profile)

on 28 Nov 2012

consider the following example, Suppose if I have a cell notation

q=cell(5,1);

And if I have different dimensions for each cell, for example

q{1} = [6 7 9 4 0 0 1 2 3 1];
q{2} = [3 5 0 4 0 0 1 2 8 1];
q{3} = [3 5 0 5 4 3 4 2 6 4 0 0 1 2 8 1];
q{4} = [4 0 0 1 2 8 1];
q{5} = [4 0 0 0 2 8];

Now if I wish to find the latest cell location containing minimum non zero value, How can I find it?

In the above example, minimum non zero value is 1 and it is present in all cells, that is, q{1} q{2} q{3} q{4} except q{5}. So here the latest cell containing 1 is q{4} and 1 is located at 4th and 7th place of q{4}. I wish to get the location details mentioning that value 1 is present in q(4,4) and q(4,7). How can I find that?

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Matt Learner

Matt Learner (view profile)

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2 Answers

Answer by Matt Fig

Matt Fig (view profile)

on 28 Nov 2012
Accepted answer
L = cellfun(@(x) find(x==1),q,'Un',0);

Now L has all the information you need.

12 Comments

Matt Fig

Matt Fig (view profile)

on 28 Nov 2012

This should do the correct thing even if you do have negatives.

mn = cellfun(@(x) min(x(x>0)),q,'Un',0);
mn = min([mn{:}])  % Show the minimum positve value.
L = cellfun(@(x) find(x==mn),q,'Un',0);
idx = find(~cellfun('isempty',L),1,'last')  % Which cell has the min.
L = L{idx} % And the positions.
Matt Fig

Matt Fig (view profile)

on 28 Nov 2012

Or, simpler

mn = cellfun(@(x) min(x(x>0)),q,'Un',0);
[mn,idx] = min(fliplr([mn{:}]));  
mn  % Show the minimum positve value.
idx = length(q) - idx + 1  % Which cell has the min.
L = cellfun(@(x) find(x==mn),q,'Un',0);
L = L{idx} % And the positions.
Matt Learner

Matt Learner (view profile)

on 28 Nov 2012

Thank you very much for your help. It completely solved my issue.

Thanks again. :)

Matt Fig

Matt Fig (view profile)

Answer by Vishal Rane

Vishal Rane (view profile)

on 28 Nov 2012

The first thing that comes to mind is

find(q{n} > 0)

It will you give you locations of elements matching the condition ' > 0' in q{n}, else it returns empty.

You could use that to build your logic.

Refer Link for examples on the find command.

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Vishal Rane

Vishal Rane (view profile)

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