ValueError: Setting an Array Element with a Sequence: Why Does This NumPy Error Occur?

ValueError: Setting an Array Element with a Sequence

When working with NumPy arrays, you occasionally encounter the error "ValueError: setting an array element with a sequence." This issue arises for two potential reasons:

Reason 1: Creating a Jagged Array

NumPy arrays require consistent dimensions throughout. Attempting to create an array from a list where the elements have different lengths will trigger this error:

np.array([[1, 2], [2, 3, 4]])         # Wrong!
np.array([[1, 2], [2, [3, 4]]])       # Wrong!

In these instances, the input lists cannot be represented as a multidimensional array with a uniform shape.

Reason 2: Incompatible Element Types

When declaring an array with a specific data type (e.g., float), you must ensure that all elements are of the same type. Mixing different types, such as strings and floats, will generate the error:

np.array([1.2, "abc"], dtype=float)   # Wrong!

If you require an array containing elements of varying types, consider using the object data type:

np.array([1.2, "abc"], dtype=object)

The above is the detailed content of ValueError: Setting an Array Element with a Sequence: Why Does This NumPy Error Occur?. For more information, please follow other related articles on the PHP Chinese website!