How to extend an array in-place in Numpy?

Question

Currently, I have some code like this

import numpy as np
ret = np.array([])
for i in range(100000):
  tmp =  get_input(i)
  ret = np.append(ret, np.zeros(len         


        

Answer 1

The usual way to handle this is something like this:

import numpy as np
ret = []
for i in range(100000):
  tmp =  get_input(i)
  ret.append(np.zeros(len(tmp)))
  ret.append(np.zeros(fixed_length))
ret = np.concatenate(ret)

For reasons that other answers have gotten into, it is in general impossible to extend an array without copying the data.