MATLAB Central Newsreader - modified unique

modified unique

gopla — Wed, 24 Oct 2007 12:54:46 -0400

Hi,
I have a array A = [ 1 2 3 3 4 5 5 5 6 6 7 8 9] and want output B
= [1 2 4 7 8 9]

i.e. select only the unique numbers from the array and discard all
numbers that get repeated in the original array.

I have tried with 'unique' and then a for loop which 'find' number of
occurrence of a element of the output of unique in the original array.
I want to simplify this and try to remove the for loop.

With Regards
Gopla

Re: modified unique

John D'Errico — Wed, 24 Oct 2007 13:02:24 -0400

gopla <gopalgajjar@gmail.com> wrote in message
<1193230486.076915.167300@z24g2000prh.googlegroups.com>...
> Hi,
> I have a array A = [ 1 2 3 3 4 5 5 5 6 6 7 8 9] and want output B
> = [1 2 4 7 8 9]
>
> i.e. select only the unique numbers from the array and discard all
> numbers that get repeated in the original array.
>
> I have tried with 'unique' and then a for loop which 'find' number of
> occurrence of a element of the output of unique in the original array.
> I want to simplify this and try to remove the for loop.

A = [ 1 2 3 3 4 5 5 5 6 6 7 8 9];

[B,count] = consolidator(A);
B(count>1) = [];

B =
     1
     2
     4
     7
     8
     9

Find consolidator on the file exchange. (Beware
the wrapped URL. Copy both lines into your
browser)

http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?
objectId=8354&objectType=file

HTH,
John

Re: modified unique

Nick Denman — Wed, 24 Oct 2007 13:04:49 -0400

Hi Gopla

gopla <gopalgajjar@gmail.com> wrote in message
<1193230486.076915.167300@z24g2000prh.googlegroups.com>...
> Hi,
> I have a array A = [ 1 2 3 3 4 5 5 5 6 6 7 8 9] and
want output B
> = [1 2 4 7 8 9]
>
> i.e. select only the unique numbers from the array and
discard all
> numbers that get repeated in the original array.
>

You may want to try histc.

> I have tried with 'unique' and then a for loop which
'find' number of
> occurrence of a element of the output of unique in the
original array.
> I want to simplify this and try to remove the for loop.
>

One possible way

A = [ 1 2 3 3 4 5 5 5 6 6 7 8 9];
AA = unique(A);
n = histc(A,AA);
AA(n==1);

> With Regards
> Gopla
>

Cheers, Nick

Re: modified unique

Lee Newman — Wed, 24 Oct 2007 13:05:45 -0400

gopla <gopalgajjar@gmail.com> wrote in message
<1193230486.076915.167300@z24g2000prh.googlegroups.com>...
> Hi,
> I have a array A = [ 1 2 3 3 4 5 5 5 6 6 7 8 9] and
want output B
> = [1 2 4 7 8 9]
>
> i.e. select only the unique numbers from the array and
discard all
> numbers that get repeated in the original array.
>
> I have tried with 'unique' and then a for loop which
'find' number of
> occurrence of a element of the output of unique in the
original array.
> I want to simplify this and try to remove the for loop.
>
> With Regards
> Gopla
>

Here's one approach that uses the tabulate function (see
help in statistics toolbox):

A = [ 1 2 3 3 4 5 5 5 6 6 7 8 9];
x=tabulate(A);
result=x(x(:,2)==1)'

I suspect there is lower-level/more concise function that
returns frequency counts that might be better than
tabulate(), but this works.

Re: modified unique

Jean-Marc Gulliet — Wed, 24 Oct 2007 13:35:24 -0400

gopla wrote:

> I have a array A = [ 1 2 3 3 4 5 5 5 6 6 7 8 9] and want output B
> = [1 2 4 7 8 9]
>
> i.e. select only the unique numbers from the array and discard all
> numbers that get repeated in the original array.
>
> I have tried with 'unique' and then a for loop which 'find' number of
> occurrence of a element of the output of unique in the original array.
> I want to simplify this and try to remove the for loop.

  One possible way is using *union* (operation on sets).

  >> A = [1 2 3 3 4 5 5 5 6 6 7 8 9];
  >> union(A,A)
  ans =
       1 2 3 4 5 6 7 8 9

  HTH,
  --
  Jean-Marc