How to generate 2d numpy array?

This works:

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

So this should work too:

nd_a = np.array([[x for x in y] for y in a])

Its very simple, do like this

import numpy as np

arr=np.arange(50)
arr_2d=arr.reshape(10,5)    #Reshapes 1d array in to 2d, containing 10 rows and 5 columns.
print(arr_2d)

To create a new array, it seems numpy.zeros is the way to go

import numpy as np
a = np.zeros(shape=(x, y))

You can also set a datatype to allocate it sensibly

>>> np.zeros(shape=(5,2), dtype=np.uint8)
array([[0, 0],
       [0, 0],
       [0, 0],
       [0, 0],
       [0, 0]], dtype=uint8)
>>> np.zeros(shape=(5,2), dtype="datetime64[ns]")
array([['1970-01-01T00:00:00.000000000', '1970-01-01T00:00:00.000000000'],
       ['1970-01-01T00:00:00.000000000', '1970-01-01T00:00:00.000000000'],
       ['1970-01-01T00:00:00.000000000', '1970-01-01T00:00:00.000000000'],
       ['1970-01-01T00:00:00.000000000', '1970-01-01T00:00:00.000000000'],
       ['1970-01-01T00:00:00.000000000', '1970-01-01T00:00:00.000000000']],
      dtype='datetime64[ns]')

See also

• How do I create an empty array/matrix in NumPy?
• np.full(size, 0) vs. np.zeros(size) vs. np.empty()