Sum the Value of Array in Hash

Sum the value of array in hash

You can use inject to sum all the amounts. You can then just put the result back into a hash if you need to.

arr = [{:amount=>10, :gl_acct_id=>1, :alt_amount=>20}, {:amount=>20, :gl_acct_id=>2, :alt_amount=>30}]    
amount = arr.inject(0) {|sum, hash| sum + hash[:amount]} #=> 30
{:amount => amount} #=> {:amount => 30}

Rails sum values in an array of hashes

You could use each_with_object with a Hash and a default value:

array = [
  {loading: 10, avg: 15, total: 25 },
  {loading: 20, avg: 20, total: 40 },
  {loading: 30, avg: 25, total: 55 }
]

sum = Hash.new(0)

array.each_with_object(sum) do |hash, sum|
  hash.each { |key, value| sum[key] += value }
end
 # => {:loading=>60, :avg=>60, :total=>120}

It will work with any number of keys, and won't complain if a key isn't present in all the hashes.

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BTW, you can replace

array.map { |h| h[:loading] }.sum

with

array.sum { |h| h[:loading] }

Sum values in array of hash if they have the same value

This seems work

array.group_by { |item| [item[:loading], item[:avg]] }.values.flat_map { |items| items.first.merge(total: items.sum { |h| h[:total] }) }
=> [{:loading=>10, :avg=>15, :total=>25}, {:loading=>20, :avg=>20, :total=>120}, {:loading=>30, :avg=>25, :total=>55}, {:loading=>10, :avg=>20, :total=>46}]

How to calculate the sum of array inside hash ruby

You should use:

total_hours = @payload[:activities].sum{|activity| activity[:hours].to_f}

You see, what you're wanting to do is, essentially:

[
  {
    :project=>1,
    :activity=>"my activity",
    :hours=>0.2e1,
    :date=>Sat, 10 Aug 2019 00:00:00 UTC +00:00
  },
  {
    :project=>2,
    :activity=>"Tester",
    :hours=>0.2e1,
    :date=>Thu, 01 Aug 2019 00:00:00 UTC +00:00
  },
  {
    :project=>2,
    :activity=>"Tester",
    :hours=>0.3e1,
    :date=>Thu, 01 Aug 2019 00:00:00 UTC +00:00
  }
].sum{|activity| activity[:hours].to_f}

But, you're calling .sum on the @payload variable, which is a hash. What you want is the value of the hash that is associated with the key :activities. Thus, you need to call .sum on @payload[:activities] where @payload[:activities] returns the array above.

Get hash values (from a number of hashes) in an array and sum them up

To sum the values of a hash:

{a:1,b:2}.values.sum
#=> 3

And to do that for your array of hashes:

total_order.flat_map(&:values).sum
#=> 15.0

Note that sum is only available in Ruby 2.4.0 and later (and in Rails). In older versions you can use reduce(:+) and inject(:+) instead of sum.

Better way to sum values in an array of hashes

I like using the map/reduce metaphor like so:

total_sales = sales.map {|s| s['sale_price']}.reduce(0, :+)

The reduce method is a synonym for the inject method, I find the name inject to be somewhat confusing with the memo component. It has another form I use above to take the initial value and a reference to a method call used for the combination/reduction process.

I think the overall pattern of mapping the values and then reducing them to an aggregate is well known and self-documenting.

EDIT: Use symbol :+ instead of proc reference &:+

How to sum the value of hashes in array with condition

One way using sum:

records.sum { |h| h["status"] ? h["number"] : 0 } #=> 10000

Get sum of key values in deep array of hashes

Regarding ruby-on-rails tag, you can use Ruby method #inject with Rails method #deep_merge:

array.inject do |hash1, hash2|
  hash1.deep_merge(hash2) do |key, hash1_val, hash2_val|
    hash1_val + hash2_val
  end
end

=> {:john=>{:win=>30, :lose=>60}, :mike=>{:win=>15, :lose=>15}}

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