How does one sort hash of hashes by multiple values?

ruby-talk
1

Imagine I have this data structure:

     @my_hash[8858]['name'] = 'goober'
     @my_hash[8858]['sort_date'] = 19991231

     @my_hash[2004]['name'] = 'goober'
     @my_hash[2004]['sort_date'] = '20010416'

     @my_hash[8872]['name'] = 'pyle'
     @my_hash[8872]['sort_date'] = '20010416'

     @my_hash[89]['name'] = 'hogan'
     @my_hash[89]['sort_date'] = '2004 0918'

     @my_hash[9]['name'] = 'homer'
     @my_hash[9]['sort_date'] = '19980718'

How does one sort it first by the name value, then by the sort_date
value? (So that the name == 'goober' items appear before the others,
and the very first element returned by the sort would be
@my_hash[8858]?)

I tried searching a bit (the FAQ and google) , but came up empty; sorry
if this is a noob question. (Although, I am a ruby noob, so...)

TIA!

Joe

2

There is probably a cleaner way to do this but...

sorted_keys = @my_hash.keys.sort do |a,b|
   next result unless res=(@my_hash[a]['name']<=>@my_hash[b]['name']) == 0
   @my_hash[a]['sort_date']<=>@my_hash[b]['sort_date']
end

Then since you have your sorted keys you can iterate over each item based on your sorted_keys array.

Zach

···

joe.yakich@gmail.com wrote:

Imagine I have this data structure:

     @my_hash[8858]['name'] = 'goober'
     @my_hash[8858]['sort_date'] = 19991231

     @my_hash[2004]['name'] = 'goober'
     @my_hash[2004]['sort_date'] = '20010416'

     @my_hash[8872]['name'] = 'pyle'
     @my_hash[8872]['sort_date'] = '20010416'

     @my_hash[89]['name'] = 'hogan'
     @my_hash[89]['sort_date'] = '2004 0918'

     @my_hash[9]['name'] = 'homer'
     @my_hash[9]['sort_date'] = '19980718'

How does one sort it first by the name value, then by the sort_date
value? (So that the name == 'goober' items appear before the others,
and the very first element returned by the sort would be
@my_hash[8858]?)

I tried searching a bit (the FAQ and google) , but came up empty; sorry
if this is a noob question. (Although, I am a ruby noob, so...)

3

require 'pp'

my_hash = Hash.new { |hash, key| hash[key] = Hash.new }

     my_hash[8858]['name'] = 'goober'
     my_hash[8858]['sort_date'] = '19991231'

     my_hash[2004]['name'] = 'goober'
     my_hash[2004]['sort_date'] = '20010416'

     my_hash[8872]['name'] = 'pyle'
     my_hash[8872]['sort_date'] = '20010416'

     my_hash[89]['name'] = 'hogan'
     my_hash[89]['sort_date'] = '20040918'

     my_hash[9]['name'] = 'homer'
     my_hash[9]['sort_date'] = '19980718'

pp my_hash.sort_by{|x| [ x.last['name'], x.last['sort_date'] ] }

---------------------------->

[[8858, {"name"=>"goober", "sort_date"=>"19991231"}],
[2004, {"name"=>"goober", "sort_date"=>"20010416"}],
[89, {"name"=>"hogan", "sort_date"=>"20040918"}],
[9, {"name"=>"homer", "sort_date"=>"19980718"}],
[8872, {"name"=>"pyle", "sort_date"=>"20010416"}]]

···

joe.yakich@gmail.com wrote:

Imagine I have this data structure:

     @my_hash[8858]['name'] = 'goober'
     @my_hash[8858]['sort_date'] = 19991231

     @my_hash[2004]['name'] = 'goober'
     @my_hash[2004]['sort_date'] = '20010416'

     @my_hash[8872]['name'] = 'pyle'
     @my_hash[8872]['sort_date'] = '20010416'

     @my_hash[89]['name'] = 'hogan'
     @my_hash[89]['sort_date'] = '2004 0918'

     @my_hash[9]['name'] = 'homer'
     @my_hash[9]['sort_date'] = '19980718'

How does one sort it first by the name value, then by the sort_date
value? (So that the name == 'goober' items appear before the others,
and the very first element returned by the sort would be
@my_hash[8858]?)

I tried searching a bit (the FAQ and google) , but came up empty; sorry
if this is a noob question. (Although, I am a ruby noob, so...)

TIA!

Joe

4

zdennis wrote:

···

joe.yakich@gmail.com wrote:

Imagine I have this data structure:

     @my_hash[8858]['name'] = 'goober'
     @my_hash[8858]['sort_date'] = 19991231

     @my_hash[2004]['name'] = 'goober'
     @my_hash[2004]['sort_date'] = '20010416'

     @my_hash[8872]['name'] = 'pyle'
     @my_hash[8872]['sort_date'] = '20010416'

     @my_hash[89]['name'] = 'hogan'
     @my_hash[89]['sort_date'] = '2004 0918'

     @my_hash[9]['name'] = 'homer'
     @my_hash[9]['sort_date'] = '19980718'

How does one sort it first by the name value, then by the sort_date
value? (So that the name == 'goober' items appear before the others,
and the very first element returned by the sort would be
@my_hash[8858]?)

I tried searching a bit (the FAQ and google) , but came up empty; sorry
if this is a noob question. (Although, I am a ruby noob, so...)

There is probably a cleaner way to do this but...

sorted_keys = @my_hash.keys.sort do |a,b|
  next result unless res=(@my_hash[a]['name']<=>@my_hash[b]['name']) == 0
  @my_hash[a]['sort_date']<=>@my_hash[b]['sort_date']
end

That should be:

sorted_keys = @my_hash.keys.sort do |a,b|
   next result unless result=(@my_hash[a]['name']<=>@my_hash[b]['name']) == 0
   @my_hash[a]['sort_date']<=>@my_hash[b]['sort_date']
end