Dealing with multiple sets

[John Henry]

Hi list,

If I have a bunch of sets:

a = set((1, 2, 3))
b = set((2, 3))
c = set((1, 3))
.....

What's the cleanest way to say:

1) Give me a list of the items that are in all of the sets? (3 in the
above example)
2) Give me a list of the items that are not in all of the sets? (1,2 in
the above example)

Thanks,

[John Henry]

Oops. Forgot to mention, I am still using 2.3.
John Henry wrote:

Hi list,

If I have a bunch of sets:

a = set((1, 2, 3))
b = set((2, 3))
c = set((1, 3))
....

What's the cleanest way to say:

1) Give me a list of the items that are in all of the sets? (3 in the
above example)
2) Give me a list of the items that are not in all of the sets? (1,2 in
the above example)

Thanks,

[Tim Peters]

[John Henry]

If I have a bunch of sets:

a = set((1, 2, 3))
b = set((2, 3))
c = set((1, 3))
....

What's the cleanest way to say:

1) Give me a list of the items that are in all of the sets? (3 in the
above example)

list(a & b & c)

2) Give me a list of the items that are not in all of the sets? (1,2 in
the above example)

list((a | b | c) - (a & b & c))

[John Henry]

Aye!

I did a:

a and b and c

Bonk!

Thanks,
Tim Peters wrote:

[John Henry]

If I have a bunch of sets:

a = set((1, 2, 3))
b = set((2, 3))
c = set((1, 3))
....

What's the cleanest way to say:

1) Give me a list of the items that are in all of the sets? (3 in the
above example)

list(a & b & c)

2) Give me a list of the items that are not in all of the sets? (1,2 in
the above example)

list((a | b | c) - (a & b & c))

[Gabriel Genellina]

At Wednesday 25/10/2006 21:12, John Henry wrote:

>Oops. Forgot to mention, I am still using 2.3.

try: set
except NameError: from sets import Set as set

and the code will work almost exactly the same in 2.3/2.4

1) Give me a list of the items that are in all of the sets? (3 in the
above example)

a & b & c
& is the intersection operator.

2) Give me a list of the items that are not in all of the sets? (1,2 in
the above example)

(a | b | c) - (a & b & c)
(take the union of all items) except (the ones that are
simultaneously in all sets)
--
Gabriel Genellina
Softlab SRL

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[Brian Beck]

John Henry wrote:

What's the cleanest way to say:

1) Give me a list of the items that are in all of the sets? (3 in the
above example)
2) Give me a list of the items that are not in all of the sets? (1,2 in
the above example)

Thanks,

If you have an arbitrary list of sets, reduce comes in handy:

See this recipe:
http://aspn.activestate.com/ASPN/Coo.../Recipe/476215

pysets = [set((1, 2, 3)), set((2, 3)), set((1, 3))]
pyreduce(set.in tersection, sets)
set([3])

pyreduce(set.un ion, sets)
set([1, 2, 3])

pyreduce(set.un ion, sets) - reduce(set.inte rsection, sets)
set([1, 2])

--
Brian Beck
Adventurer of the First Order

[John Henry]

Oh, great. Learn something new everyday.

For this, what I did was to build up a string, and then use eval on the
string. Very ugly.

Now I can simply do a reduce.

Thanks,

Brian Beck wrote:

John Henry wrote:

What's the cleanest way to say:

1) Give me a list of the items that are in all of the sets? (3 in the
above example)
2) Give me a list of the items that are not in all of the sets? (1,2 in
the above example)

Thanks,

If you have an arbitrary list of sets, reduce comes in handy:

See this recipe:
http://aspn.activestate.com/ASPN/Coo.../Recipe/476215

pysets = [set((1, 2, 3)), set((2, 3)), set((1, 3))]
pyreduce(set.in tersection, sets)
set([3])

pyreduce(set.un ion, sets)
set([1, 2, 3])

pyreduce(set.un ion, sets) - reduce(set.inte rsection, sets)
set([1, 2])

--
Brian Beck
Adventurer of the First Order