Delete all repeatation number

Hi matlab community,

Say i have the matrix:

a = [1 2 2 3 2 4 5 6 7 8 6]

and i want delete all repetation number there, so i want like this result:

a = [1 3 4 5 7 8]

you can see, i want remove number 2 and 6..how to solve it?

and another problem (if we work with big array).. say i have information that repeat number are 2 and 6, any suggestions for a looping construct? below looping is fail!

repeat=[2;6];
a = [1 2 2 3 2 4 5 6 7 8 6]
for i=1:length(repeat)
a(a==a(repeat(i)))=[]
end

from these looping, will result:

a =

     1     3     4     5     6     8     6

you can see, that result still produce repeat number, namely 6. .tks community :)

Answer 1

[Jan]

% Your code
repeat=[2;6];
a = [1 2 2 3 2 4 5 6 7 8 6]
for i=1:length(repeat)
   a(a==a(repeat(i)))=[]
end

A small modification solves the promlem:

for i=1:length(repeat)
   a(a == repeat(i)) = [];
   % not a(repeat(i)) !
end

Or easier:

a(ismember(a, [2,6])) = []

or

a = setdiff(a, [2,6], 'stable')

[eko supriyadi]

tks jan for your effort, included in 2 solutions too

Answer 2

[Stephen23]

a = [1,2,2,3,2,4,5,6,7,8,6];
[c,x] = histc(a,unique(a));
a(c(x)>1) = []

a = 1×6

1 3 4 5 7 8

Answer 3

[Bruno Luong]

a = [1 2 2 3 2 4 5 6 7 8 6]

a = 1×11

1 2 2 3 2 4 5 6 7 8 6

[u,~,j]=unique(a);
a(ismember(a,u(accumarray(j,1)>1)))=[]

a = 1×6

1 3 4 5 7 8

[Jan]

Or with omitting ismember:

a = [17 2 2 3 2 4 5 6 7 8 6];

[~, ~, ic] = unique(a);
mult       = (accumarray(ic, 1) <= 1);
as         = a(mult(ic))

as = 1×6

17 3 4 5 7 8

Answer 4

[KSSV]

REad about unique.

a = [1 2 2 3 2 4 5 6 7 8 6] 

a = 1×11

1 2 2 3 2 4 5 6 7 8 6

iwant = unique(a)

iwant = 1×8

1 2 3 4 5 6 7 8

[eko supriyadi]

no no i want delete all repetation number..

so i will produce:

a = [1 3 4 5 7 8]

Answer 5

[Jan]

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

[S, idx] = sort(a(:).');
m        = [false, diff(S) == 0];
ini      = strfind(m, [false, true]);
m(ini)   = true;        % Mark 1st occurence in addition
T(idx)   = m;           % TRUE for multiple occurences

b = a(~T)

b = 1×6

1 3 4 5 7 8