In [3]: a = np.arange(0,20,1).reshape(4,5)

In [4]: a
Out[4]:
array([[ 0,  1,  2,  3,  4],
       [ 5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14],
       [15, 16, 17, 18, 19]])

# 始点1, 終点3
In [5]: a[1:3,:]
Out[5]:
array([[ 5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14]])

# 間隔2
In [6]: a[::2,:]
Out[6]:
array([[ 0,  1,  2,  3,  4],
       [10, 11, 12, 13, 14]])

# 間隔-1 => 反転
In [7]: a[::-1,:]
Out[7]:
array([[15, 16, 17, 18, 19],
       [10, 11, 12, 13, 14],
       [ 5,  6,  7,  8,  9],
       [ 0,  1,  2,  3,  4]])

# 始点3, 終点1, 間隔-1
In [9]: a[3:1:-1,:]
Out[9]:
array([[15, 16, 17, 18, 19],
       [10, 11, 12, 13, 14]])