python,arrays,sorting,replace,average , Averaging indexes of peaks if they are close in Python

## Question:

Tag: python,arrays,sorting,replace,average

This might be a simple problem but I haven't come up with a solution. Say I have an array as `np.array([0,1,0,1,0,0,0,1,0,1,0,0,1])` with peaks at indexes `[1,3,7,9,12]`. How can I replace the indexes with `[2,8,12]`, that is, averaging indexes close in distance, if a threshold distance between peaks is set to be greater than `2` in this example?

Please note that the binary values of the array are just for illustration, the peak value can be any real number.

You could use Raymond Hettinger's cluster function:

``````from __future__ import division

def cluster(data, maxgap):
"""Arrange data into groups where successive elements
differ by no more than *maxgap*

>>> cluster([1, 6, 9, 100, 102, 105, 109, 134, 139], maxgap=10)
[[1, 6, 9], [100, 102, 105, 109], [134, 139]]

>>> cluster([1, 6, 9, 99, 100, 102, 105, 134, 139, 141], maxgap=10)
[[1, 6, 9], [99, 100, 102, 105], [134, 139, 141]]
"""
data.sort()
groups = [[data[0]]]
for item in data[1:]:
val = abs(item - groups[-1][-1])
if val <= maxgap:
groups[-1].append(item)
else:
groups.append([item])
return groups

peaks = [1,3,7,9,12]
print([sum(arr)/len(arr) for arr in cluster(peaks, maxgap=2)])
``````

yields

``````[2.0, 8.0, 12.0]
``````

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