查找每个序列连续编号的起点和终点Matlab

Question

Let say, I have A=[1 1 1 4 4 4 4 4 1 1 2 2 1 1 2 2 1 1 1 3 3 3 3 3] . The series number is B=[1:24] My question is how can I find the start and end for every consecutive number. Should be start and end point of my answer is

for A=1 is 1,3;9,10;13,14;17,19
for A=2 is 11,12;15,16
for A=3 is 20,24
for A=4 is 4,8`

Answer 1

Something like:

n = 1;
B = find(diff([0,A==n,0]));         %//Find where sequences of n and not  begin
B(2:2:end) = B(2:2:end) - 1       %//Change from the beginning of not n sequence to the end of the n sequence
reshape(B, 2, [])'

OR now that you want 2 columns it's easier (and more logical) to do this:

s = find(diff([0,A==n,0])==1);
e = find(diff([0,A==n,0])==-1) -1;
B = [s', e']