Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
NCTM or The Math Forum.



Finding endpoints for runs
Posted:
Jan 26, 2013 8:26 PM


Dear all: I'm trying to find the endpoints for runs of numbers based on a vector. Let
>> Y = [1 3 4 6 7 8]
Y =
1 3 4 6 7 8
I want an output vector Z of size(length(Y),2) where
Z =
0 2 2 5 2 5 5 9 5 9 5 9
Here is the idea behind what I want.
The first element of Y is 1, which is not followed by the next integer; thus, the integers that "surround" the integer 1 are 0 and 2, the first row of Z.
The second element of Y is 3, which is followed by the next integer, 4. However there is a break after 4. Thus, the run of consecutive integers 3 and 4 is "surrounded" by the integers 2 and 5. Therefore, the next two rows of Z, corresponding to the two elements 3 and 4 of Y, are [2 5].
Likewise, the last three elements of Y are consecutive integers, "surrounded" by the integers 5 and 9. Hence the last three rows of Z are [5 9].
Thanks for your help!



