I have a collection of objects, which i want to separate into groups
based on a particular property (to be specific, two attributes - that is
if obj.foo and obj.bar are both the same for two objects they go into an
array together). Not every object has a duplicate, but most of them do.
So, i'd end up with an array, where each member is another array, with
the subarrays holding either 1 or 2 (or maybe more) objects that match
on foo and bar.
Can anyone tell me a nice and simple way of doing this?
thanks
max
···
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Posted via http://www.ruby-forum.com/.
Enumerable#parition or Set#classify might help.
-- fxn
···
On Jan 21, 2008, at 12:23 PM, Max Williams wrote:
I have a collection of objects, which i want to separate into groups
based on a particular property (to be specific, two attributes - that is
if obj.foo and obj.bar are both the same for two objects they go into an
array together). Not every object has a duplicate, but most of them do.
So, i'd end up with an array, where each member is another array, with
the subarrays holding either 1 or 2 (or maybe more) objects that match
on foo and bar.
Can anyone tell me a nice and simple way of doing this?
Xavier Noria wrote:
Can anyone tell me a nice and simple way of doing this?
Enumerable#parition or Set#classify might help.
-- fxn
hmmm...i couldn't work out how to make it easier with either of those.
I ended up doing this, which isn't very clever but it did seem to work.
groups =
vals = collection.collect{|obj| [obj.val1, obj.val2]}.uniq!
for val in vals
groups << collection.select{|obj| obj.val1 == val[0] && obj.val2 =
val[1]
end
···
On Jan 21, 2008, at 12:23 PM, Max Williams wrote:
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Posted via http://www.ruby-forum.com/\.
The activesupport gem, which is part of Rails, but can be used
separately, adds an Enumerable#group_by method which does pretty much
what you are asking for if I understand correctly.
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On Jan 21, 2008 8:07 AM, Max Williams <toastkid.williams@gmail.com> wrote:
Xavier Noria wrote:
> On Jan 21, 2008, at 12:23 PM, Max Williams wrote:
>
>>
>> Can anyone tell me a nice and simple way of doing this?
>
> Enumerable#parition or Set#classify might help.
>
> -- fxn
hmmm...i couldn't work out how to make it easier with either of those.
I ended up doing this, which isn't very clever but it did seem to work.
groups =
vals = collection.collect{|obj| [obj.val1, obj.val2]}.uniq!
for val in vals
groups << collection.select{|obj| obj.val1 == val[0] && obj.val2 =
val[1]
end
--
Rick DeNatale
My blog on Ruby
http://talklikeaduck.denhaven2.com/
Xavier Noria wrote:
Can anyone tell me a nice and simple way of doing this?
Enumerable#parition or Set#classify might help.
-- fxn
hmmm...i couldn't work out how to make it easier with either of those.
I ended up doing this, which isn't very clever but it did seem to work.
groups =
vals = collection.collect{|obj| [obj.val1, obj.val2]}.uniq!
for val in vals
groups << collection.select{|obj| obj.val1 == val[0] && obj.val2 =
val[1]
Note there is an assignment instead of an equals operator there.
end
Yes, I think that's equivalent to
collection.to_set.classify {|x| [x.foo, x.bar]}.values
plus perhaps a map to_a.
-- fxn
···
On Jan 21, 2008, at 2:07 PM, Max Williams wrote:
On Jan 21, 2008, at 12:23 PM, Max Williams wrote:
Rick Denatale wrote:
The activesupport gem, which is part of Rails, but can be used
separately, adds an Enumerable#group_by method which does pretty much
what you are asking for if I understand correctly.
--
Rick DeNatale
My blog on Ruby
http://talklikeaduck.denhaven2.com/
Ah right, i see now 
cheers!
···
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Posted via http://www.ruby-forum.com/\.
Xavier Noria wrote:
Note there is an assignment instead of an equals operator there.
end
Yes, I think that's equivalent to
collection.to_set.classify {|x| [x.foo, x.bar]}.values
plus perhaps a map to_a.
-- fxn
That's not really my code, it's a paraphrased version for clarity
Cheers for the tip about to_set.classify though.
···
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