Python - Subtracting the Elements of Two Arrays
I can't replicate this but it looks like the numbers are 8 bit and wrapping some how
I am new to Python programming and stumbled across this feature of subtracting in python that I can't figure out.  I have two 0/1 arrays, both of size 400.  I want to subtract each element of array one from its corresponding element in array 2.  
For example say you have two arrays A = [0, 1, 1, 0, 0] and B = [1, 1, 1, 0, 1].
Then I would expect A - B = [0 - 1, 1 - 1, 1 - 1, 0 - 0, 0 - 1] = [-1, 0, 0, 0, -1]
However in python I get [255, 0, 0, 0, 255].
Where does this 255 come from and how do I get -1 instead?
Here's some additional information:
The real variables I'm working with are Y and LR_predictions.
Y = array([[0, 0, 0, ..., 1, 1, 1]], dtype=uint8)
LR_predictions = array([0, 1, 1, ..., 0, 1, 0], dtype=uint8)
When I use either Y - LR_predictions or numpy.subtract(Y, LR_predictions) 
I get: array([[  0, 255, 255, ...,   1,   0,   1]], dtype=uint8)
Thanks