How to compute a xi-xj matrix in numpy without loops (by api calls)?
Here's what to start with:
import numpy as np
x = np.random.rand(4)
xij = np.matrix([xi-xj for xj in x for xi in x]).reshape(4,4)
By reshaping the array, you can use the minus operator to calculate what you want
import numpy as np x = np.random.rand(4) x = x.reshape(-1,1) xij = np.matrix(x.T - x)