Removing repeated in order elements from array?

3 views (last 30 days)
I have an array like [ 1 1 1 2 2 3 3 3 1 1 1 2 2 4 4 4 5 5 6]
Is there a method which will produce array [ 1 2 3 1 2 4 5 6] and remove all repeating orderly values but not remove all duplicates?
have tried code below with no luck
for k=length(array):-1:1
if array(k)==array(k+1)
array(k)=[]
end
end

Answers (2)

Rik
Rik on 30 Mar 2022
No need for a loop (even if you should have replaced length by numel):
data=[ 1 1 1 2 2 3 3 3 1 1 1 2 2 4 4 4 5 5 6];
L=diff(data)==0; % note: this is 1 element shorter that data itself
data(L)=[]
data = 1×8
1 2 3 1 2 4 5 6

Voss
Voss on 30 Mar 2022
Your approach will work; you just have to start at the second-to-last element instead of the last:
array = [ 1 1 1 2 2 3 3 3 1 1 1 2 2 4 4 4 5 5 6];
for k=length(array)-1:-1:1
if array(k)==array(k+1)
array(k)=[];
end
end
array
array = 1×8
1 2 3 1 2 4 5 6
Here's another approach:
array = [ 1 1 1 2 2 3 3 3 1 1 1 2 2 4 4 4 5 5 6];
array(diff(array) == 0) = [];
array
array = 1×8
1 2 3 1 2 4 5 6
  3 Comments
Torsten
Torsten on 30 Mar 2022
Edited: Torsten on 30 Mar 2022
Why not ? I get
array = [2]
It's because diff(array) has one element less than array.
Voss
Voss on 30 Mar 2022
As @Torsten says, it should still work (both ways work):
array = [2 2 2 2 2 2 2];
for k=length(array)-1:-1:1
if array(k)==array(k+1)
array(k)=[];
end
end
array
array = 2
array = [2 2 2 2 2 2 2];
array(diff(array) == 0) = [];
array
array = 2

Sign in to comment.

Categories

Find more on Data Type Conversion in Help Center and File Exchange

Products


Release

R2021b

Community Treasure Hunt

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

Start Hunting!