Finding consecutive segments in a pandas data frame

Question

I have a pandas.DataFrame with measurements taken at consecutive points in time. Along with each measurement the system under observation had a distinct state at each point

Answer 1

You could use np.diff() to test where a segment starts/ends and iterate over those results. Its a very simple solution, so probably not the most performent one.

a = np.array([3,3,3,3,3,4,4,4,4,4,1,1,1,1,4,4,12,12,12])

prev = 0
splits = np.append(np.where(np.diff(a) != 0)[0],len(a)+1)+1

for split in splits:
    print np.arange(1,a.size+1,1)[prev:split]
    prev = split

Results in:

[1 2 3 4 5]
[ 6  7  8  9 10]
[11 12 13 14]
[15 16]
[17 18 19]