[EMAIL PROTECTED] wrote: > Hi Steve! > I am not sure if I was clear with my previous post .Ok let me rephrase > it . > > Assume the values list is the > content of a histogram. Then we see that > values = [ 0, 72, 2, 4, 9, 2, 0, 0, 42, 26, 0, 282, > 23, 0, 101, 0, 0, 0, 0, 0] > > 1 is repeated 72 times, 3 -> 4 times and so on. That is the index > would be the value repeated as many times as in the list. > Now If we find the max and look for the adjcent index. > > That is if we plot the above list as a histogram. We will have crests > and troughs ie peaks and dips. if we find two dips then the region > between the two dips could be a range like [0, 72, 2] .So here we > are not looking for a zero. But if we find dips then we consider the > regions between it as a bin and group it. > > | /\ > | /\ / \ /\ > | / \/ \/ \ > |/_____________________________________ > |----|-----|---| > 1 2 3 > > so pictorially. In the above plot. If y axis is the list above. then we > need to bin it this way. > If I use you previous approach using the groupby then all these three > regions will be considered as one. > > Hope I am clear this time.
So you want the peaks and valleys basically. Well, using itools.window from http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/299529, you could do something like: py> values = [0,72,2,4,9,2,0,0,42,26,0,282,23,0,101,0,0,0,0,0] py> peaks = [i ... for i, (v1, v2, v3) in enumerate(itools.window(values)) ... if v1 < v2 and v2 > v3] py> peaks [1, 4, 8, 11, 14] py> valleys = [i ... for i, (v1, v2, v3) in enumerate(itools.window(values)) ... if v1 >= v2 and v2 <= v3] py> valleys [2, 6, 7, 10, 13, 15, 16, 17, 18] py> [(min((abs(p - v), v) for v in valleys + [0] if v < p)[1], ... p, ... min((abs(p - v), v) for v in valleys if v > p)[1]) ... for p in peaks] [(0, 1, 2), (2, 4, 6), (7, 8, 10), (10, 11, 13), (13, 14, 15)] This is not likely the most efficient approach, but it's pretty simple: * identify the peaks and valleys * identify the valley on each side of a peak STeVe -- http://mail.python.org/mailman/listinfo/python-list
