On Mon, 2013-02-25 at 22:04 -0500, josef.pktd@gmail.com wrote:
On Mon, Feb 25, 2013 at 9:58 PM, <josef.pktd@gmail.com> wrote:
On Mon, Feb 25, 2013 at 9:20 PM, Sebastian Berg <sebastian@sipsolutions.net> wrote:
On Mon, Feb 25, 2013 at 10:43 AM, Till Stensitzki <mail.till@gmx.de> wrote:
First, sorry that i didnt search for an old thread, but because i
disagree with
conclusion i would at least address my reason:
<snip> Two small things (not sure if it matters much). But first almost all of
On Mon, 2013-02-25 at 10:50 -0500, Skipper Seabold wrote: these methods are related to the container and not the elements. Second actually using a method arr.abs() has a tiny pitfall, since abs would work on numpy types, but not on python types. This means that:
np.array([1, 2, 3]).max().abs()
works, but
np.array([1, 2, 3], dtype=object).max().abs()
breaks. Python has a safe name for abs already...
(np.array([1, 2, 3], dtype=object)).max() 3 (np.array([1, 2, 3], dtype=object)).__abs__().max() 3 (np.array([1, 2, '3'], dtype=object)).__abs__() Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: bad operand type for abs(): 'str'
map(abs, [1, 2, 3]) [1, 2, 3] map(abs, [1, 2, '3']) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: bad operand type for abs(): 'str'
or maybe more useful
from decimal import Decimal d = [Decimal(str(k)) for k in np.linspace(-1, 1, 5)] map(abs, d) [Decimal('1.0'), Decimal('0.5'), Decimal('0.0'), Decimal('0.5'), Decimal('1.0')]
np.asarray(d).__abs__() array([1.0, 0.5, 0.0, 0.5, 1.0], dtype=object) np.asarray(d).__abs__()[0] Decimal('1.0')
Josef
I don't see a difference.
(I don't expect to use max abs on anything else than numbers.)
The difference is about scalars only. And of course __abs__ is fine, but if numpy adds an abs method, its scalars would logically have it too. But then you diverge from python scalars. That has exactly the downside that you may write code that suddenly stops working for python scalars without noticing. I turned around the abs and max order here, so that the abs works on the scalar, not useful but just as an example.
Josef
I find myself typing things like
arr.abs()
and
arr.unique()
quite often.
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