# Basic syntax:
np.ones((number_rows, number_cols), dtype=int)

# Example usage:
import numpy as np
np.ones((5, 3), dtype=int)
array([[1, 1, 1],
       [1, 1, 1],
       [1, 1, 1],
       [1, 1, 1],
       [1, 1, 1]])

# Note, use np.zeros to create an array of zeros