MATLAB - Remove Leading and Trailing Zeros From a

问题:

I have a wavelet function with leading and trailing zeros. I would like to strip all the zeros which occur before or after the wavelet. However, I would not like to remove any zeros within the wavelet itself. To simplify, let's say I have the following 1x11 vector:

0 0 0 -2 -1 0 -1 -2 0 0 0

After removing leading and trailing zeros the vector should be:

-2 -1 0 -1 -2

My actual vectors are large and performance is my primary concern. I am a MATLAB novice and would appreciate any tips on how to accomplish this task as efficiently as possible.

回答1:

Try this

 y = x(find(x,1,'first'):find(x,1,'last'));

The find(x,1,'option') command gives you first and last non-zero indices.

回答2:

i1 = find(X, 1, 'first')

will give you the index of the first non-zero element of X

i2 = find(X, 1, 'last') 

will give you the index of the last one. Then

X(i1:i2)

will give you the array with the leading and trailing zeros stripped.