Determining 20 elements either side of each of my elements in my new array

So I have 3 arrays of data:

• y_arr: which are my 4000 y values
• x_arr: which are my 4000 corresponding x values
• height_arr: which are my 14 x and y minima values which I have obtained from my x_arr and y_arr.

What I want to do now is find the 20 values either side each of my 14 height_arr values, where these data points lie within the y_arr and x_arr datasets.

Here is what I have come up with and failed at:

transit_curves = []
for i in range(0, len(height_list)):
    b = section_x_arr > height_list[i][0]
    c = section_y_arr < height_list[i][1]
    transit_curves.append([b,c])

print(transit_curves)

Result:

[[array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])], [array([False, False]), array([False, False])]]