As stated I want to return the positions of the maximum value of the array. For instance if I have the array:
A = np.matrix([[1,2,3,33,99],[4,5,6,66,22],[7,8,9,99,11]])
np.argmax(A) returns only the first value which is the maximum, in this case this is 4. However how do I write code so it returns [4, 13]. Maybe there is a better function than argamax() for this as all I actually need is the position of the final maximum value.
Find the max value of the array and then use np.where.
>>> m = a.max()
>>> np.where(a.reshape(1,-1) == m)
(array([0, 0]), array([ 4, 13]))
After that, just index the second element of the tuple. Note that we have to reshape the array in order to get the indices that you are interested in.
Since you mentioned that you're interested only in the last position of the maximum value, a slightly faster solution could be:
A.size - 1 - np.argmax(A.flat[::-1])
Here:
A.flat is a flat view of A.
A.flat[::-1] is a reversed view of that flat view.
np.argmax(A.flat[::-1]) returns the first occurrence of the maximum, in that reversed view.
