Add a description string to a numpy array

Question

I'd like to add a description to a python numpy array.

For example, when using numpy as an interactive data language, I'd like to do something like:

A = np.array([[1,2,3],[4,5,6]])
A.description = "Holds all the data from experiment 1. Each row contains an intensity measurement with the following columns: time [s], intensity [W/m^2], error [%]."

But it gives:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'numpy.ndarray' object has no attribute 'description'

Is this possible without subclassing the numpy.ndarray class?

Regards, Jonas

Answer 1

Simplest way would be to use a namedtuple to hold both the array and the description:

>>> from collections import namedtuple
>>> Array = namedtuple('Array', ['data', 'description'])
>>> A = Array(np.array([[1,2,3],[4,5,6]]), "Holds all the data from experiment 1. Each row contains an intensity measurement with the following columns: time [s], intensity [W/m^2], error [%].")
>>> A.data
array([[1, 2, 3],
       [4, 5, 6]])
>>> A.description
'Holds all the data from experiment 1. Each row contains an intensity measurement with the following columns: time [s], intensity [W/m^2], error [%].'