Removing a bunch of elements from a 1-D vector?

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Dheeraj Kapur 2016-1-19

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https://ww2.mathworks.cn/matlabcentral/answers/264292-removing-a-bunch-of-elements-from-a-1-d-vector

编辑： Stephen23 2016-1-22

I have a large 1-D vector and want to delete ten consecutive elements after the first or second or third one (depending on the signal undergoing processing). For example if my starting vector is x = [1,2,3,4,5,6,7,8,9,10,11........10,000], I want to create another vector which looks like: y = [1,(delete ten elements),12, (delete ten elements),23,(delete ten elements),34,....]. What is the best way to do such an operation?

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Answer 1

Stephen23 2016-1-22

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https://ww2.mathworks.cn/matlabcentral/answers/264292-removing-a-bunch-of-elements-from-a-1-d-vector#answer_207057

编辑：Stephen23 2016-1-22

在 MATLAB Online 中打开

Use basic matrix indexing to select the elements that you want to keep:

>> X = randi(9,1,23)
X =
   3   5   4   4   5   7   8   9   2   4   3   3   2   6   7   5   9   1   8   2   9   4   1
>> start = 3;
>> step = 5;
>> X(start:step:end)
ans =
   4   9   2   1   1

Or for the original example:

>> Y = 1:10000;
>> start = 3;
>> step = 11;
>> Y(start:step:end)
ans =
 Columns 1 through 14:
      3     14     25     36     47     58     69     80     91    102    113    124    135    146
  etc

Note that using indexing actually selects the values from the input vector.

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Dheeraj Kapur 2016-1-22

This is precisely what I was looking to do. Thank you! Seems quite straight-forward when I look at it now.

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Answer 2

Stalin Samuel 2016-1-19

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https://ww2.mathworks.cn/matlabcentral/answers/264292-removing-a-bunch-of-elements-from-a-1-d-vector#answer_206640

在 MATLAB Online 中打开

x = [1:1000];
gap = 10;%no of elements to be deleted
y = [min(x):gap+1:max(x)]

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Dheeraj Kapur 2016-1-19

This works fine if I need to start with the first element of parent vector. Is there a way to do the same operation, say from the third element? As in, new vector looks something like y = [1,2,3,(delete 10 elements),14,(delete 10 elements), 25,....]. I was looking to get this done in the same way that we use to remove one element at a time. For eg x(3:5:end)=[] removes just one element. Can we use something along these lines to remove 10 elements at one go?

Stephen23 2016-1-22

编辑：Stephen23 2016-1-22

@Dheeraj Kapur: this does not actually answer your question, because it does not select elements of the input vector as your original question requests, but instead creates an entirely new vector using the colon operator. This method will fail completely for any vector that is not a sequential sequence of integers with a step of one.

If you want a solution that actually selects elements of the input vector, regardless of their values, then see my answer. My method actually answers your question.

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