Ruby group_by object?

Question

I have an array or different objects and I want to group by objects. For example

 => [#<Graphic id: 3...">, #<Collection id: 1....">, #<Category id:...">, #<Volume id: 15...">] 
 all.size
 => 4 

I tried

all.group_by(Object) 

but that didn't work...any ideas on how to groupby objects in one array?

Solution

Are you looking to do something like this?

all.group_by(&:class)

Which will group the objects in array by their class name

EDIT for comment

all.group_by(&:class).each do |key, group|
   group.each{|item| puts item}
end

Key is the grouping element and obj is the collection for the key, so this would loop through each group in the grouping and list the objects within that group

Also you could sort within the groupings pretty easily too

all.group_by(&:class).each do |key, group|
    group.sort_by(&:attribute).each{|item| puts item}
end

Comments

[Matt Elhotiby]

yes but that gives me an ordered hash ...how do i use that in the view. I want to display all the Collections first then all the Graphics and so on....so basically i want to use this array to group by the models and then loop through them but how do you loop through this .... => #<OrderedHash {Category(i

[Matt Elhotiby]

thanks Jimmy that is a great answer...do you know how to group them into 4 arrays all with the appropriate objects...so for example one array with @graphics and the next with @collections and so on...