Use np.empty to initialize an empty array and define the axis you want to append across: import numpy as np mat = np.empty((0,2)) for i in ... ... <看更多>

Reproducing code example: np.append is extremely slow, why is that the case? The docs don't have anything on the performance part. ... <看更多>

The issue is not with append but rather the assignment (bindings) of numpy arrays as pointers to the same location in memory. ... <看更多>