Performing method call on object stored in array Ruby

Question

I am trying to call the method details for object Person that is storred in array resut but keep getting this error undefined method 'details' for [#<Person:0x000001e277d58aa8 @name="Winston", @age=3>, #<Person:0x000001e277d58940 @name="Rob", @age=1>, #<Person:0x000001e277d58788 @name="Sam", @age=5>]:Array (NoMethodError)

This is the code that is throwing the error result.each { |p| p.details}. It is the last line of code. I am not sure why this is throwing an error and am even more confused becuase I made similar method calls earlier and they are not throwing errors.

class Person
  def initialize(name, age)
    @name = name
    @age = age
  end

  def details
    puts "Name: #{@name}\nAge: #{@age}"
  end

  def get_age
    return @age
  end
end

def generate_data(names)
  sample_pool = []

  names.each { |n| sample_pool << Person.new(n, rand(100)) }

  return sample_pool
end

def extract(sample_pool, criteria)
  result = []
  result << sample_pool.select { |n| n.get_age <= criteria}
  return result
end

names = ["Doug", "Matt", "Fred", "Fransisco", "Pete", "Rick", "Rob", "Tanner", "Greg", "Sherri", "Winston", "Sam", "Brett", "Georgia", "Alison", "Grant", "Brick", "Slick", "Van", "Fawn", "Sloan", "Harry", "Ron", "Jerry", "Jasmine", "Dawn", "Misty"].shuffle!

puts "Enter an age that you would like to search up too."
criteria = gets.chomp.to_i
sample_pool = generate_data(names)
result = extract(sample_pool, criteria)

result.each { |p| p.details}

Tony Arra · Accepted Answer · 2022-04-16 20:20:26Z

2

select returns an array, and << pushes the return value of select into result.

This means that result is a nested array. It looks like this:

[[Person<name: rob>, Person<name: Sam>, Person<name: Winston>]]

You want to create a flat array, so you could change extract to be something like this:

def extract(sample_pool, criteria)
  sample_pool.select { |n| n.get_age <= criteria}
end

edited Apr 16, 2022 at 20:20

answered Apr 15, 2022 at 0:19

Tony Arra

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3 Comments

Trevor Matheson Over a year ago

That last code snippet for extract that you put returns the evaluation of sample_pool.select { |n| n.get_age <= criteria }, is that correct?

Tony Arra Over a year ago

Correct - which would be a flat array containing all of the elements of sample_pool matching the criteria.

Trevor Matheson Over a year ago

So I was doing something similar were I used .each and storred it in an array in the generate_data method. But it looks like .select returns an array so that is why I was storring an array inside an array.

nPn · Accepted Answer · 2022-04-16 16:20:13Z

0

TonyArra answered your original question by modifying your extract method, but you mentioned in your comment, your generate_data method.

The use of the each method in generate_data adds a single Person for each name in your names Array, so you get what you expect, however a better way to implement that is to use map to "map" the String Array names into a Person Array

def generate_data(names)
    names.map {|n| Person.new(n, rand(100))}
end

answered Apr 16, 2022 at 16:20

nPn

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