How to delete elements in array efficiently

Hi all,

I'm writing a simple script in Matlab where I compare adjacent element and delete one of them if there difference between them is one.

for i=1:length(Vector) - 1
if Vector(i+1) - Vector(i) == 1
    Vector(i) = [];
end
 if i == length(Vector) 
    break
 end

However, I'm getting an error that my indices are out of bound. Is there a simpler way of doing this by utilizing internal functions. I think my problem is that my array is constantly decreasing and the Vector(i+1) - Vector(i) are out of bounds.

Answer 1

[Azzi Abdelmalek]

Vector=[1 2 4 5 66 88 100 101]
id=find([0 diff(Vector)]==1)-1
Vector(id)=[]

Answer 2

[dpb]

When doing such in loops, start at end and work to beginning -- then the indices of those removed are above where you're headed next.

But, in Matlab use vector operations and supplied functions to do such things...

 v([false diff(v)==1])=[];

Answer 3

[Azzi Abdelmalek]

You can also do it with while loop

Vector=[1 2 3 4 5 66 88 100 101 14]
i=1;
while i<numel(Vector)
  if Vector(i+1) - Vector(i) == 1
      Vector(i) = [];
      i=i-1;
  end
  i=i+1
end
Vector

[dpb]

Or, variations on a theme, the looping solution...

for i=length(v):-1:2
  if v(i)-v(i-1)==1;
    v(i)=[];
  end
end

[Azzi Abdelmalek]

The result is not the same, because this will keep the first number of the consecutive numbers

[Jan]

Repeated shrinking of an array suffers from the same inefficiency as iterative growing.

[dpb]

Posted simply as pedagogical example for OP, not as recommended solution--see earlier posting.