Why do I get “Field elements” error in my array initialization?

I try to do this

import numpy as np
a = np.array([1,2,3,4],[5,6,7,8])

and I get this:

TypeError                                 Traceback (most recent call last)
<ipython-input-12-ac428719fc97> in <module>
      1 import numpy as np
----> 2 a = np.array([1,2,3,4],[5,6,7,8])

TypeError: Field elements must be 2- or 3-tuples, got '5'


The problem is that all the data needs to go into the first argument, and what you want to be the second row is now being read as the specification of the data type (because that’s what the second argument of the array constructor is for).

If the array you are trying to create is:

[[1 2 3 4] [5 6 7 8]]

then your code should be:

a = np.array([[1,2,3,4],[5,6,7,8]])