[Numpy-discussion] how to do this efficiently?
Neal Becker
ndbecker2@gmail....
Wed Feb 9 09:35:57 CST 2011
Zachary Pincus wrote:
>> In a 1-d array, find the first point where all subsequent points
>> have values
>> less than a threshold, T.
>
> Maybe something like:
>
> last_greater = numpy.arange(arr.shape)[arr >= T][-1]
> first_lower = last_greater + 1
>
> There's probably a better way to do it, without the arange, though...
I'm trying to find the first point in a power spectrum such that all subsequent
points are below some level. I've started with:
db is my power spectrum in dB, It is already reversed.
mag = np.maximum.accumulate (db) - db[-1]
Now all I need is to find the first point such that mag < -50. How to do this
efficiently?
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