Numpy——1. Creation of array

Create array

np.array(object, dtype) or np.arange(start, stop, step, dtype)

object： The object of the created array , Can be a single value , list , Cell, etc .
example：

dtype: data type

1. Specify the data type
   example：
   
   2. Adjust the data type
   a.astype("i1")
   3. Modify the number of floating-point numbers
   np.round(array, d)