面膜与numpy isin

Question

I want to make a mask with numpy array I've foun a function, but it doesn't make what I want.Here is the code example.

np.isin([1,2,3,4,5,8,6,1,1],[1,2,3,5,1])

This code returns this:

array([ True,  True,  True, False,  True, False, False,  True,  True], dtype=bool)

But I want the same output except the last value of output array to be False. Because I need exact mask of sequence( [1,2,3,5,1] ) in this order and no longer than its len

Answer 1

You can turn elements after certain amount of True s to zero with:

mask[mask.cumsum() > 5] = False
#                    ^ length of the second array

---

import numpy as np
mask = np.isin([1,2,3,4,5,8,6,1,1],[1,2,3,5,1])

mask[mask.cumsum() > 5] = False
mask
# array([ True,  True,  True, False,  True, False, False,  True, False], dtype=bool)