Hi all, I am not sure if this is of help for anyone. I wrote some code to find the relative maxima in a 1D array for my own purpose. Maybe someone is interested or even finds a bug *g*. I post the code here and appreciate any feedback. Even "stop spamming your buggy code" :-)
from numpy import diff, sign, convolve, array, where, around, int32, alen
def localmaxima_at(x): '''Returns the indices of local maxima in the 1D array x.
If several elements in x have the same value, then the index of the element in the middle is returned.
If there are two adjacent elements with the same value, one of them is returned.
x[0] and x[-1] are never returned as an index for the local maximum.
@Author: Samuel John @copyright: http://creativecommons.org/licenses/by-nc-sa/3.0/ @todo: unittests ''' assert len(x) > 2, "Length of x should be greater than two in order to define a meaningful local maximum." assert x.ndim == 1, "Expected 1D array." #print 'x=\n',x filled=sign(diff(x)).astype(int32) # fill zeros: has_zeros = (filled == 0).any() last = 0 if has_zeros: for i in xrange(alen(filled)): if filled[i] == 0: filled[i] = last else: last = filled[i] #print 'filled\n',filled left = where( convolve( filled, array([-1,1]), mode='full' ) -2 == 0 )[0]
if has_zeros: filled=sign(diff(x)).astype(int32) last = 0 for i in reversed(xrange(len(filled))): if filled[i] == 0: filled[i] = last else: last = filled[i]
right = where( convolve( filled, array([-1,1]), mode='full' ) -2 == 0 )[0] #print 'left\n',left #print 'right\n',right return around( (left + right) / 2.0).astype(int32)
bests, Samuel