[Numpy-discussion] dtype always copies

[Stefan v. d. W. <st...@su...>]

Hi all,

I've noticed that 'astype' always forces a copy.  Is this
behaviour intended?  It seems to conflict with 'asarray', that
tries to avoid a copy.

For example, when wrapping code in ctypes, the following snippet
would have been useful:

def foo(x):
    # ensure x is an array of the right type
    x =3D N.ascontiguousarray(x).astype(N.intc)

but that will cause a copy, so you'll have to do

def foo(x):
    try:
        x =3D N.ascontiguousarray(x,N.intc)
    except:
        x =3D N.ascontiguousarray(x).astype(N.intc)

Maybe I'm missing something obvious here -- any pointers?

Thanks
St=E9fan