How to group elements of sub-arrays based on two elements

I have an input as follows:

input = [
["account1",10,"Dr"],
["account1",20,"Dr"],
["account2",15,"Cr"],
["account1",25,"Cr"],
["account2",10,"Dr"],
["account1",10,"Cr"]
]


I am trying to get the sums by account and transaction type, i.e., Dr or Cr. I need an output as below:

Dr

Cr

output =
["account1","Dr"] => 30,
["account1","Cr"] => 35,
["account2","Dr"] => 10,
["account2","Cr"] => 15



I can sum the amount based on only account using:

input.each_with_object(Hash.new(0))
# => "account1"=>65, "account2"=>25


3 Answers
3

You can do so:

input.each_with_object(Hash.new(0)) (f,g,i), h

=> ["account1", "Dr"]=>30, ["account2", "Cr"]=>15, ["account1", "Cr"]=>35, ["account2", "Dr"]=>10


input.group_by acc,_,title.
transform_values
#=> ["account1", "Dr"]=>30, ["account2", "Cr"]=>15, ["account1", "Cr"]=>35,
# ["account2", "Dr"]=>10


The first step is the following.

input.group_by acc,_,title
#=>
# ["account1", "Dr"]=>[["account1", 10, "Dr"], ["account1", 20, "Dr"]],
# ["account2", "Cr"]=>[["account2", 15, "Cr"]],
# ["account1", "Cr"]=>[["account1", 25, "Cr"], ["account1", 10, "Cr"]],
# ["account2", "Dr"]=>[["account2", 10, "Dr"]]
#


output = Hash.new(0) # set a default value of zero, avoiding nil
input.each do |account, amount, transaction|
output[[account, transaction]] += amount
end

output # ["account1", "Dr"]=>30, ["account2", "Cr"]=>15, ["account1", "Cr"]=>35, ["account2", "Dr"]=>10


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