CODEWITHSUNDEEP
rubyarraysjsonhashgrouping
bmalets
bmalets

Reputation: 3297

How add new key into array of json hashes?

I have a big array like:

[
{id: 1, name: 'abs', surname: 'abs'},
{id: 1, name: 'abs', surname: 'abs'},
...
{id: 1, name: 'abs', surname: 'abs'},
]

and I need to add new 'group' key into each hash. First five hashes should have 'group': 1, second five hashes should have 'group': 2 e.g. to get in result array:

[
{id: 1, name: 'abs', surname: 'abs', group: 1},
{id: 1, name: 'abs', surname: 'abs', group: 1},
{id: 1, name: 'abs', surname: 'abs', group: 1},
{id: 1, name: 'abs', surname: 'abs', group: 1},
{id: 1, name: 'abs', surname: 'abs', group: 1},
{id: 1, name: 'abs', surname: 'abs', group: 2},
...
{id: 1, name: 'abs', surname: 'abs', group: N},
]

If I use Array#group_by and Array#each_with_index methods code works slow, cause array have many records... How can I do it using ruby to make code run faster?

Upvotes: 0

Views: 63

Answers (2)

bmalets
bmalets

Reputation: 3297

how about:

foo = [
  {id: 1, name: 'abs', surname: 'abs'},
  {id: 1, name: 'abs', surname: 'abs'},
  {id: 1, name: 'abs', surname: 'abs'},
  {id: 1, name: 'abs', surname: 'abs'},
]
group_count =5

foo.each_with_index do |u,i|
  u['highlight_group'] = i.div( group_count ) 
end

puts foo

Upvotes: 0

the Tin Man
the Tin Man

Reputation: 160551

I reduced your input sample because there was no need for that large of a sample. You can interpolate how to do what you need from this code:

require 'json'

foo = [
  {id: 1, name: 'abs', surname: 'abs'},
  {id: 1, name: 'abs', surname: 'abs'},
  {id: 1, name: 'abs', surname: 'abs'},
  {id: 1, name: 'abs', surname: 'abs'},
]

foo.each_slice(2).with_index(1){ |a, i| a.each{ |h| h[:group] = i } }
puts foo.to_json
# >> [{"id":1,"name":"abs","surname":"abs","group":1},{"id":1,"name":"abs","surname":"abs","group":1},{"id":1,"name":"abs","surname":"abs","group":2},{"id":1,"name":"abs","surname":"abs","group":2}]

Here's what it looks like broken out to be more readable:

puts JSON::pretty_generate(foo)
# >> [
# >>   {
# >>     "id": 1,
# >>     "name": "abs",
# >>     "surname": "abs",
# >>     "group": 1
# >>   },
# >>   {
# >>     "id": 1,
# >>     "name": "abs",
# >>     "surname": "abs",
# >>     "group": 1
# >>   },
# >>   {
# >>     "id": 1,
# >>     "name": "abs",
# >>     "surname": "abs",
# >>     "group": 2
# >>   },
# >>   {
# >>     "id": 1,
# >>     "name": "abs",
# >>     "surname": "abs",
# >>     "group": 2
# >>   }
# >> ]

Here's what is happening:

  • each_slice slices up the array into N-sized chunks.

    pp foo.each_slice(2).to_a
# >> [[{:id=>1, :name=>"abs", :surname=>"abs", :group=>1},
# >>   {:id=>1, :name=>"abs", :surname=>"abs", :group=>1}],
# >>  [{:id=>1, :name=>"abs", :surname=>"abs", :group=>2},
# >>   {:id=>1, :name=>"abs", :surname=>"abs", :group=>2}]]

  • with_index adds an incrementing value to the list of parameters passed into the block. That is being assigned to i in the block.

    pp foo.each_slice(2).with_index(1).to_a
# >> [[[{:id=>1, :name=>"abs", :surname=>"abs", :group=>1},
# >>    {:id=>1, :name=>"abs", :surname=>"abs", :group=>1}],
# >>   1],
# >>  [[{:id=>1, :name=>"abs", :surname=>"abs", :group=>2},
# >>    {:id=>1, :name=>"abs", :surname=>"abs", :group=>2}],
# >>   2]]

Upvotes: 1

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