How to detect a sign change for elements in a numpy array
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Published on 2010-04-16T11:04:40Z
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I have a numpy array with positive and negative values in.
a = array([1,1,-1,-2,-3,4,5])
I want to create another array which contains a value at each index where a sign change occurs (For example, if the current element is positive and the previous element is negative and vice versa).
For the array above, I would expect to get the following result
array([0,0,1,0,0,1,0])
Alternatively, a list of the positions in the array where the sign changes occur or list of booleans instead of 0's and 1's is fine.
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