Find boolean mask by pattern

Question

I have array:

arr = np.array([1,2,3,2,3,4,3,2,1,2,3,1,2,3,2,2,3,4,2,1])
print (arr)
[1 2 3 2 3 4 3 2 1 2 3 1 2 3 2 2 3 4 2 1]

I would like

Answer 1

We can simplify things at the end with Scipy supported binary-dilation -

from scipy.ndimage.morphology import binary_dilation

m = (rolling_window(arr, len(pat)) == pat).all(1)
m_ext = np.r_[m,np.zeros(len(arr) - len(m), dtype=bool)]
out = binary_dilation(m_ext, structure=[1]*N, origin=-(N//2))

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For performance, we can bring in OpenCV with its template matching capability, as we are basically doing the same here, like so -

import cv2

tol = 1e-5
pat_arr = np.asarray(pat, dtype='uint8')
m = (cv2.matchTemplate(arr.astype('uint8'),pat_arr,cv2.TM_SQDIFF) < tol).ravel()