Clear Filters
Clear Filters

Delete all repeatation number

2 views (last 30 days)
eko supriyadi
eko supriyadi on 1 Jun 2022
Commented: eko supriyadi on 1 Jun 2022
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 :)

Accepted Answer

Jan
Jan on 1 Jun 2022
% 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')
  1 Comment
eko supriyadi
eko supriyadi on 1 Jun 2022
tks jan for your effort, included in 2 solutions too

Sign in to comment.

More Answers (4)

Stephen23
Stephen23 on 1 Jun 2022
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

Bruno Luong
Bruno Luong on 1 Jun 2022
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
  1 Comment
Jan
Jan on 1 Jun 2022
Edited: Jan on 1 Jun 2022
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

Sign in to comment.


KSSV
KSSV on 1 Jun 2022
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
  1 Comment
eko supriyadi
eko supriyadi on 1 Jun 2022
no no i want delete all repetation number..
so i will produce:
a = [1 3 4 5 7 8]

Sign in to comment.


Jan
Jan on 1 Jun 2022
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

Categories

Find more on Loops and Conditional Statements in Help Center and File Exchange

Products


Release

R2021a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!