Add set operations to Series objects

[cpcloud]

from this SO question

[hayd]

Would this just be on the Series values (i.e. ignore index)?

I had a look in algos and couldn't see anything (np intersect1d seems slow).

OT but a weird thing from that Q is that you can't call Series on a set.

[cpcloud]

yet a frozenset works....werid...i would've though that frozenset was a subclass of set, guess not

[cpcloud]

well it doesn't work...it returns a frozenset...

[hayd]

(I don't see why we enforce this, list is happy to take a set, why shouldn't Series?)

[cpcloud]

because there's no way to map indices to set, they are arbitrary since a set object is unordered

[hayd]

ha! Series let's a lot of stuff drop through.... eg. Series(1)

[cpcloud]

but you're right....list does it so there must be some arbitrary indices assigned

[cpcloud]

i just discovered that Series takes generators! i had no idea.

[hayd]

and that's the workaround, right? pass it to list first... kinda sucks Also isn't a dict similarly unordered (and yet we allow that) :s

Interestingly I thought we used np.fromiter to do that, but apparently it's just list.

[cpcloud]

but dict has keys which are used as the index

[cpcloud]

i guess it's a workaround, but how else would you do it?

[cpcloud]

i made the change....nothing breaks...i'll submit

[cpcloud]

for set construction that is

[cpcloud]

#4482

[jreback]

fyi...the Series(1) stuff is getting squash in #3862 (by #3482), its just odd