CODEWITHSUNDEEP
ruby-on-railsruby
Alex Antonov
Alex Antonov

Reputation: 15146

array of hashes sort by

I have a big array of hashes:

array = [
  {color: '5 absolute', ... },
  {color: '5.0', ... },
  {color: '5.1', ... },
  {color: 'last', ... },
  {color: '50', ... },
  {color: '5 elite', ... },
  {color: 'edge'}
]

I need colors to ordered:

5 absolute
5 elite
5.0
5.1
50
edge
last

The priority is:

first going spaces ' ',
then dots '.',
then digits '7',
then other 'string'

This is like SQL activerecord analog query, but I don't want that difficult query in the background. I want this logic. How can I do this using AR query?

Upvotes: 0

Views: 87

Answers (3)

Jonas Elfström
Jonas Elfström

Reputation: 31428

You could always just sort the array of hashes.

array.map{|h| h[:color]}.sort
=> ["5 absolute", "5 elite", "5.0", "5.1", "50", "edge", "last"]

The following first sorts by number and then by the string after the number.

array = [{color: '5 absolute'}, {color: '5.0'}, {color: '5.1'}, 
         {color: 'last'}, {color: '50'}, {color: '5 elite'}, 
         {color: 'edge'}, {color: '6 absolute'}, {color: '7'}]

array.map{|h| h[:color]}.sort_by do |s|
  n = s.to_f
  if n == 0 && s.match(/\d/).nil?
    n = Float::INFINITY
  end
  [n, s.split(" ")[-1]]
end
=> ["5.0", "5 absolute", "5 elite", "5.1", "6 absolute", "7", "50", "edge", "last"]

Upvotes: 1

hirolau
hirolau

Reputation: 13901

From you question it is very hard to tell what you want. Especially since the order you ask for is exactly the same one a normal sort would create.

I any case, here is a way of creating a "custom sort" order the way you wanted. The difference between this and a regular sort is that in this sort can make certain types of characters or sets of characters triumph others.

array = [
  {color: '5 absolute'},
  {color: '5.0'},
  {color: '50 hello'},
  {color: 'edge'}
]
p array.sort_by{|x| x[:color]} #=> [{:color=>"5 absolute"}, {:color=>"5.0"}, {:color=>"50 hello"}, {:color=>"edge"}]
# '50 hello' is after '5.0' as . is smaller than 0.

Solving this problem is a bit tricky, here is how I would do it:

# Create a custom sort order using regexp:
# [spaces, dots, digits, words, line_endings]
order  = [/\s+/,/\./,/\d+/,/\w+/,/$/]

# Create a union to use in a scan:
regex_union = Regexp.union(*order)

# Create a function that maps the capture in the scan to the index in the custom sort order:
custom_sort_order = ->x{
 x[:color].scan(regex_union).map{|x| [order.index{|y|x=~y}, x]}.transpose
}

#Sort:
p array.sort_by{|x| custom_sort_order[x]}
# => [{:color=>"5 absolute"}, {:color=>"50 hello"}, {:color=>"5.0"}, {:color=>"edge"}]

Upvotes: 0

phoet
phoet

Reputation: 18835

so like this?

h = [{:color=>"5 absolute"},
 {:color=>"5.0"},
 {:color=>"5.1"},
 {:color=>"last"},
 {:color=>"50"},
 {:color=>"5 elite"},
 {:color=>"edge"}]

h.map(&:values).flatten.sort
# => ["5 absolute", "5 elite", "5.0", "5.1", "50", "edge", "last"]

or all the other answers...

Upvotes: 0

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