how to comapre multiple arrays - and colorcode them

i'm not sure how to describe this - I am trying to color code multiple arrays.

array_1 = np.array([[0,0,0],
                    [0,0,0],
                    [0,0,0]])

array_2 = np.array([[1,0,0],
                    [0,0,0],
                    [0,0,0]])

array_3 = np.array([[1,1,1],
                    [0,0,0],
                    [0,1,1]])

array_2 should be close to array_1, and array_3 should be farther away - but how do you represent this in a colormap?

i guess i can calculate pairwise difference and use a square or absolute vlaue of that, and the sum that to get a single value which could be used to refrence a colormap.
But this is problematic since a new array_4:

array_4 = np.array([[0,0,0],
                    [0,0,0],
                    [0,0,1]])

would get the same color as array_2 when compared to array_1

I am wandering if there is a common/simple/more efficient way to do this.

thanks in advance!