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arraysmatlabmatrix
fronthem
fronthem

Reputation: 4139

How to get the most frequent values from list in MATLAB (but multiple values)?

From 1 dimensional matrix:

list_A = [1,2,4,6,7,7,7,9,10,11,11,11,13,13,13]

How can i get the list of number that have a highest occurrence (in this case occurrence = 3)

The answer that i want should be like this (if we use list_A):

Ans = [7,11,13]

Upvotes: 0

Views: 2528

Answers (2)

Luis Mendo
Luis Mendo

Reputation: 112659

You can do it most easily with mode. To get all values you should use the third output, which will be a cell array:

[~, ~, result] = mode(list_A);
result = result{1}.';

EDIT

If your vector is already sorted and you want to exploit that (which mode apparently doesn't do), you can do it manually with diff, find and max:

ii = find(diff([list_A inf]));
dii = diff(ii);
result = list_A(ii(find(dii==max(dii))+1));

Upvotes: 3

Robert Seifert
Robert Seifert

Reputation: 25232

use hist:

I assumed your vector A is sorted.

A = [1,2,4,6,7,7,7,9,10,11,11,11,13,13,13];
occ = 3;

out = A( hist(A,A) == occ )

gives:

out =

     7    11    13

If A is not sorted, you could sort it of course, or:

A = [7,7,7,1,2,4,6,9,10,11,11,11,13,13,13]
occ = 3;

out = find( histc(A,1:max(A)) == occ )

If there are also negative numbers:

A = [7,7,7,-4,6,-9,10,-11,-11,-11,13,13,13,-20]
occ = 3;

out = find( histc(A,min(A):max(A)) == occ ) + min(A)-1

or the simple version is working too:

A = sort(A);
out = A( hist(A,A) == occ )

>> out =  -11     7    13

Another convenient way is to use the tabulate function of the Statistics Toolbox, which would even work for decimal values!

A = [7.5,7.5,7.5,-4,6,-9,10,-11,-11,-11,13,13,13,-20]
occ = 3;

T = tabulate(A);
out = T(T(:,2) == occ  ,1)

>> out =

  -11.0000
    7.5000
   13.0000

Upvotes: 4

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