How to group array of hashes and create nested array after keyword?

Question

How to group array of hashes into one "groupname" and "id" hash and push elements occurring after "words" keyword into array of hashes? I can't find similar issue.

My flat input:

[{
    "id" => "1",
    "groupname" => "Unit 1",
    "words" => nil,
    "unit" => "1",
    "name" => "asdfwe"
}, {
    "id" => "1",
    "groupname" => "Unit 1",
    "words" => nil,
    "unit" => "1",
    "name" => "testasdf"
}, {
    "id" => "2",
    "groupname" => "Unit 2",
    "words" => nil,
    "unit" => "2",
    "name" => "test2wewe"
}, {
    "id" => "2",
    "groupname" => "Unit 2",
    "words" => nil,
    "unit" => "2",
    "name" => "test2sadf"
}]

Desired output:

[{
    "id" => "1",
    "groupname" => "Unit 1",
    "words" => [{
        "unit" => "1",
        "name" => "asdfwe"
    }, {
        "unit" => "1",
        "name" => "testasdf"
    }]
}, {
    "id" => "2",
    "groupname" => "Unit 2",
    "words" => [{
        "unit" => "2",
        "name" => "test2wewe"
    }, {
        "unit" => "2",
        "name" => "test2sadf"
    }]
}]

Current not working as expected steps:

out = []
arrhsh.each_with_index do |hsh,index|
  hsh.each do |(k,v)|
    if k === "words"
      newhsh = {}
      newhsh["id"] = hsh["id"]
      newhsh["groupname"] = hsh["groupname"]
      newhsh["words"] = []
      wordshsh = {
        "unit" => hsh["unit"],
        "name" => hsh["name"]
      }
      newhsh["words"] << wordshsh
      out << newhshq
    end
  end
end
out.group_by {|h| h["id"]}

Have you tried something?

Roman Kiselenko
– Roman Kiselenko

2015-04-14 10:59:41 +00:00
Commented Apr 14, 2015 at 10:59 — Roman Kiselenko
– Roman Kiselenko, Commented Apr 14, 2015 at 10:59
only group_by one key.

luzny
– luzny

2015-04-14 11:04:38 +00:00
Commented Apr 14, 2015 at 11:04 — luzny
– luzny, Commented Apr 14, 2015 at 11:04
please include your attempts.

Roman Kiselenko
– Roman Kiselenko

2015-04-14 11:05:29 +00:00
Commented Apr 14, 2015 at 11:05 — Roman Kiselenko
– Roman Kiselenko, Commented Apr 14, 2015 at 11:05

Ameen · Accepted Answer · 2015-04-14 12:21:08Z

1

What about this?

b = a.group_by { |i| i['id'] }.map do |id, group|
  {
    id: id,
    groupname: group.first['groupname'],
    words: group.map { |g| g.slice('unit', 'name') }
  }
end

answered Apr 14, 2015 at 12:21

Ameen

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1 Comment

Tucker Over a year ago

g.slice('unit', 'name') produces an error because there is no slice method in the Hash class. words: group.map { |g| g.select { |k,_| k.match(/\bname\b|\bunit\b/) } } fixes this problem.

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