Find a block of ones in a vector

Hi,

I have a simple question but no matlab command for this :). I have a vector containing zeros and ones. I want to find every beginning of a block containing only of ones. For example: 000110011100. I want to get 4 and 8 as the indices indicating the beginning of a block with only ones.

Thank you for your efforts.

Answer 1

[Fangjun Jiang]

a=[0 0 0 1 1 0 0 1 1 1 0 0]
ind=find(diff(a)==1)+1

Not too fast. This won't work if a starts with 1. Use this instead

a=[1 1 0 0 0 1 1 0 0 1 1 1 0 0]
ind=find(diff([0 a])==1)

[fcarl]

Great :) diff is exactly which i was searching for :)

[Fangjun Jiang]

See my update.

[Andrei Bobrov]

ind = strfind([0 a],[0 1])

Answer 2

[fcarl]

I recognized this ;) the function was helpfull :)