How to iterate over a list and append all the results to an array

Question

I want to extract the values from "all", for which the first columns is 0 or 1.

arr = np.zeros((0,2))
for num in [0,1]:
    spike = np.vstack((arr, all[all[:,0] == num] ))
print(spike)

When i print "spike" only the values of 1 are present.

Answer 1

您在循环中覆盖了spike的值。