python - apply a function to each pair of rows of an array -

I have a numpy array of sizes 4x400 . I want to apply the function to all pairs of rows of this narrow array. Function:

  def func (vector1, vector2): ... ... return x  

where X is a Float value

Then in the end I will get a vector of 10.

Is it anyhow efficiently (fast) without using loops? Imported itertools as imported into arr = numpy.random.rand (4,400)

  Transposed = arr.T values ​​= [Numpy.dot (i, j) i, j (transposed, 2)] print value in it.comb