Explanation of “ValueError: must have equal len keys and value when setting with an ndarray”
This error occurs when you try to set a value for a dictionary using an ndarray (NumPy array) as keys, but the lengths of the ndarray and the corresponding values are not equal.
Here’s an example to illustrate this error:
import numpy as np
keys = np.array([1, 2, 3]) # ndarray with 3 elements
values = np.array([10, 20]) # ndarray with 2 elements
my_dict = {}
my_dict[keys] = values # Trying to set values using ndarray keys
# Output:
# ValueError: must have equal len keys and value
In the above example, we have an ndarray “keys” with 3 elements and an ndarray “values” with 2 elements. When we try to set the values in the dictionary “my_dict” using the ndarray as keys, it raises a ValueError because the lengths of the keys and values are not equal.
To fix this error, you need to ensure that the lengths of the ndarray keys and the corresponding values are equal. Here’s an example of the corrected code:
import numpy as np
keys = np.array([1, 2, 3]) # ndarray with 3 elements
values = np.array([10, 20, 30]) # ndarray with 3 elements
my_dict = {}
my_dict[keys] = values # Setting values using ndarray keys
# Output:
# {1: 10, 2: 20, 3: 30}
In the above corrected example, both the “keys” and “values” ndarrays have the same length (3), so the values are successfully set in the dictionary “my_dict”.