[Numpy-discussion] how to do this efficiently?
Alan G Isaac
alan.isaac@gmail....
Wed Feb 9 11:17:45 CST 2011
On 2/9/2011 11:39 AM, Bruce Southey wrote:
> np.argmax(x>5) # doesn't appear to be correct
It was an answer to the particular question
of how to do find_first, which it does
(at the cost of a boolean array):
it finds the first element greater than 5.
>>> x
array([5, 4, 3, 6, 7, 3, 2, 1])
>>> np.argmax(x>5)
3
>>> x[3]
6
You can also find the first element less than 4, etc.
>>> np.argmax(x<4)
2
The condition should be chosen for the problem.
As Josef pointed out, the usefulness
of this and other approaches
can depend on the monotonicity
of the series.
fwiw,
Alan
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