Find index within full array of the argmax of an array subset-CodePudding

Goal: to find the index of the highest value in 1d array from index 25 to [-1]

The way I do it is wrong, I get the index of the highest value of the slice.

If there is no other way than slicing it, how do I then get the correct index of the original array?

ipython code example

CodePudding user response：

If you know you're indexing the array from index 25 on, you could add 25 to the result:

argmax = close[25:].argmax()   25

But if you're using an arbitrary slice of your array, another way to do this would be to create a similar array of indices, then slice that the same way:

indices = np.arange(len(close))
# some complicated slicing
sliced = close[2:-7:4]
# apply the same slicing:
sliced_indices = indices[2:-7:4]

# now, get the index in the original array of the argmax from the subset
argmax = sliced_indices[sliced.argmax()]