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Brian_Alexander
Asked: 2020-05-10 09:56:36 +0800 CST 2020-05-10 09:56:36 +0800 CST

How do I sum the values ​​of a hash set into an array in ruby?

  • 772

I have an array personas[]that contains the data of many people, in each hash, that is, each person has their own hash. I want to add the values ​​of all the ages, and tried several things without results.

persona = {nombre:a, edad:b, comuna:c, género:d }
ruby

3 Answers

  1. You can add the ages like this:

    #Array de Personas
personas = [ 
             { nombre: 'hugo', edad: 8 }, 
             { nombre: 'paco', edad: 9 }, 
             { nombre: 'luis', edad: 10},
           ]

personas.map { |persona| persona[:edad] }.inject(:+)
# => 27

    This works like this:

    First you have the array personasthat contains the hashes of each person, then we iterate through that array using the method mapto get the age of each person with persona[:edad]and finally we apply inject(:+)that is going to sum all the values ​​that we passed, in this case, all the ages.

    • 2
  2. Best Answer

    It should be added that Ruby from the version 2.4adds the method Enumerable#sum, which as the name indicates, adds all the elements of a Enumerable:

    personas = [
  { nombre: 'hugo', edad: 8 },
  { nombre: 'paco', edad: 9 },
  { nombre: 'luis', edad: 10 }
]

personas.sum { |persona| persona[:edad] }
#=> 27

    Greetings.

    • 2

  3. Another option is to use reduce(or inject) with a block, which is more efficient since the array is traversed only once:

    personas  = [
  { nombre: "hugo", edad: 8 },
  { nombre: "paco", edad: 9 },
  { nombre: "luis", edad: 10 }
]

personas.reduce(0) { |sum, persona| sum += persona[:edad] }
#=> 27
    • 1