I have this data structure resulted from a query grouping
{
[0, "AR"]=>2,
[0, nil]=>1,
[0, "AQ"]=>6,
[1, nil]=>4,
[1, "AQ"]=>3,
[2, "BG"]=>1,
[2, nil]=>1,
}
I want to manipulate it so I end up with a structure grouped like this
{
0 => {
'AR' => 2,
'AQ' => 6,
nil => 1
},
1 => {
'AQ' => 1,
nil => 4
},
2 => {
'BG' => 1,
nil => 1
}
}
input = {
[0, "AR"]=>2,
[0, nil]=>1,
[0, "AQ"]=>6,
[1, nil]=>4,
[1, "AQ"]=>3,
[2, "BG"]=>1,
[2, nil]=>1,
}
result = {}
input.each do |k, v|
if result[k[0]]
result[k[0]].merge!({ k[1] => v })
else
result[k[0]] = { k[1] => v }
end
end
puts result
#{0=>{"AR"=>2, nil=>1, "AQ"=>6}, 1=>{nil=>4, "AQ"=>3}, 2=>{"BG"=>1, nil=>1}}
I think this is not the most succinct way, I hope some advice!
hash = {
[0, "AR"]=>2,
[0, nil]=>1,
[0, "AQ"]=>6,
[1, nil]=>4,
[1, "AQ"]=>3,
[2, "BG"]=>1,
[2, nil]=>1,
}
new_hash = {}
hash.each{|k, v| new_hash[k[0]] ||= {}; new_hash[k[0]].merge!({k[1] => v})}
puts new_hash # {0=>{"AR"=>2, nil=>1, "AQ"=>6}, 1=>{nil=>4, "AQ"=>3}, 2=>{"BG"=>1, nil=>1}}
Here is one more very similar to previous answers but with using of #each_with_object:
hash = {
[0, "AR"]=>2,
[0, nil]=>1,
[0, "AQ"]=>6,
[1, nil]=>4,
[1, "AQ"]=>3,
[2, "BG"]=>1,
[2, nil]=>1,
}
result_hash = Hash.new { |h,k| h[k] = {} }
hash.each_with_object(result_hash) do |((parrent_key, key), value), res|
res[parrent_key].merge!(key => value)
end
=> {0=>{"AR"=>2, nil=>1, "AQ"=>6}, 1=>{nil=>4, "AQ"=>3}, 2=>{"BG"=>1, nil=>1}}
I came up with an answer that doesn't require additional variable assignments in its enclosing scope (it has "referential transparency": https://en.wikipedia.org/wiki/Referential_transparency)
input
.group_by { |(arr, num)| arr.first }
.each_with_object(Hash.new) do |(key, vals), hsh|
vals.each do |((key, innerkey), innerval)|
hsh[key] ||= {}
hsh[key][innerkey] = innerval
end
hsh
end
# {0=>{"AR"=>2, nil=>1, "AQ"=>6}, 1=>{nil=>4, "AQ"=>3}, 2=>{"BG"=>1, nil=>1}}
Two high-level steps:
#group_by to create a hash with that structure.# output of `#group_by` on first array element:
key: 0, vals: [ [[0, "AR"], 2], [[0, nil], 1], [[0, "AQ"], 6] ]
key: 1, vals: [ [[1, nil], 4], [[1, "AQ"], 3] ]
key: 2, vals: [ [[2, "BG"], 1], [[2, nil], 1] ]
#each_with_object to construct the nested hashes. For each vals array above, I extracted the second and third values by destructuring the arrays in the block parameter (((key, innerkey), innerval)) and then the hash assignment was straightforward.
