## How can I count the occurrences of each element in a vector in MATLAB?

### MathWorks Support Team (view profile)

on 11 Jan 2012
Latest activity Commented on by Walter Roberson

### Walter Roberson (view profile)

on 16 Aug 2017
Accepted Answer by MathWorks Support Team

### MathWorks Support Team (view profile)

I would like to be able to return the count of occurences of each element in a vector.

For example if I have a vector:

`   x=[10 25 4 10 9 4 4]`

I expect the result to be

` y=[2 1 3 2 1 3 3].`

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MathWorks Support

### MathWorks Support Team (view profile)

on 7 Aug 2017

While there is no single function in MATLAB to count occurrences of each element, there are a few ways to count elements in a vector:

1. Logical Indexing:

The following code snippet will give the desired output:

```y = zeros(size(x));
for i = 1:length(x)
y(i) = sum(x==x(i));
end
```

For MATLAB R2016b and later, you can use implicit expansion to further simplify the code:

```y = sum(x==x')
```

2. Binning:

You can use the "hist" and "unique" functions as shown here to do the same:

```x = [10 25 4 10 9 4 4]
[a,b]=hist(x,unique(x))
```

3. Third-Party Tools:

For another workaround, see the following file, 'CountMember.m', that was contributed by a MATLAB user to do the same from a single function:

Note that MathWorks does not guarantee or warrant the use or content of submissions to the MATLAB Central File Exchange. Any questions, issues, or complaints should be directed to the contributing author.

Show 1 older comment
Riyasat

### Riyasat (view profile)

on 23 Nov 2014

the above comment is Exactly true.. as I faced the exam same problem while looking for a solution..

shashika iresh

### shashika iresh (view profile)

on 4 Oct 2016

how to reduce 2 3 3 4 4 4 2 matrix to 2 3 4 2

Paolo Binetti

### Paolo Binetti (view profile)

on 29 Jan 2017

Solution 2 does not produce the desired output. The answer by Andrei Bobov below does.

### Andrei Bobrov (view profile)

on 14 Aug 2014

```[a,b] = histc(x,unique(x));
y = a(b);
```

Harshavardhan Thyagarajan

### Harshavardhan Thyagarajan (view profile)

on 3 Aug 2015

I'm working with a small variant of the original problem, where I want it to count the number of occurrences of each whole number till 13.

So if my input is

x = [1,1,1,2,4,5,5]

I need an output

y = [3,1,0,1,2]

How do I do this?

Andrei Bobrov

### Andrei Bobrov (view profile)

on 3 Aug 2015

y = accumarray(x(:),1)

Harshavardhan Thyagarajan

### Harshavardhan Thyagarajan (view profile)

on 3 Aug 2015

Thanks Andrei, that works!

### Julian Hapke (view profile)

on 1 Jun 2017
Edited by Julian Hapke

### Julian Hapke (view profile)

on 1 Jun 2017

here is another one:

```sum(bsxfun(@eq,x,x'),1)
```

or if you want the output to be the same orientation as input

```sum(bsxfun(@eq,x,x'),(size(x,2)==1)+1)
```

Johannes Korsawe

### Johannes Korsawe (view profile)

on 1 Jun 2017

the second solution exhibits pathological tendencies...

### Josh (view profile)

on 14 Aug 2014

This is kind of awkward since it requires using the input array within the anonymous function, but:

```y = arrayfun(@(t)nnz(x==t), x);
```

should do the trick, too.

### mittal54 (view profile)

on 16 May 2015
Edited by Walter Roberson

### Walter Roberson (view profile)

on 16 Aug 2017

```numbers=unique(v);       %list of elements
count=hist(v,numbers);   %provides a count of each element's occurrence
```

this will give counts. and if you want to have a nice graphical representation then try this

```bar(accumarray(v', 1))
```

Walter Roberson

### Walter Roberson (view profile)

on 16 May 2015

When using hist() pay attention to Dan's comment above pointing out a flaw in the approach. This flaw is not shared by Andrei's histc approach above.

### lamghari (view profile)

on 30 Nov 2015

Hi, I want to count the number of followed occurrences of each element in a vector.

So if my input is

x = [1 1 1 2 2 1 1 2 5 5]

I need an output

y = [1 2 1 2 5;3 2 2 1 2] How do I do this?

Andrei Bobrov

### Andrei Bobrov (view profile)

on 30 Nov 2015
```y = [x(t); diff([find(t),numel(x)+1])]
```
Jan Simon

### Jan Simon (view profile)

on 29 Jan 2017
```[B, N] = RunLength(X);
Y      = [B; N]
```

### Truong Phan (view profile)

on 16 Aug 2017

I need help to count the occurrences of each element in a matrix. Thanks

Walter Roberson

### Walter Roberson (view profile)

on 16 Aug 2017
```[uvals, ~, uidx] = unique(YourArray);
output = [uvals, accumarray(uidx, 1)];
```

This would produce an N x 2 array with the first column being the unique array values and the second column being the associated count.