Question

Is there a simple way to create an immutable NumPy array?

If one has to derive a class from ndarray to do this, what’s the minimum set of methods that one has to override to achieve immutability?

Answer 1

You can make a numpy array unwriteable:

a = np.arange(10)
a.flags.writeable = False
a[0] = 1
# Gives: ValueError: assignment destination is read-only

Also see the discussion in this thread:

http://mail.scipy.org/pipermail/numpy-discussion/2008-December/039274.html

and the documentation:

http://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.flags.html