CODEWITHSUNDEEP
ruby
Ernesto G
Ernesto G

Reputation: 545

Evaluating values and returning coordinates in a 2d array

I'm trying to program a method that would loop through a 2d array and return the coordinates of the elements that comply with a given condition (in this case, element value == 1):

def eval(array)
  array.each_index do |x|
    x.each_index do |y|
     if array[x][y] == 1 then 
      puts "X: #{x} Y: #{y}"
     end
   end
 end
end

array = [
[1, 0, 0, 0],
[0, 1, 0, 0],
[1, 0, 0, 1],
[0, 1, 0, 0]
]
eval(array)

I'm getting this error:

block in eval': undefined method `each_index' for 0:Fixnum (NoMethodError)

Any tips on what might be happening?

Upvotes: 2

Views: 171

Answers (2)

threaz
threaz

Reputation: 403

array.each_index do |x|

captures this index into x variable and then you are trying to use each_index on number. Namely

x.each_index do |y|

Fixing this issue gives us the function:

def findMatchingCords(array)
  array.each_index do |x|
    array[x].each_index do |y|
     if array[x][y] == 1 then 
      puts "X: #{x} Y: #{y}"
     end
   end
 end
end

Now findMatchingCords(array) yields

X: 0 Y: 0
X: 1 Y: 1
X: 2 Y: 0
X: 2 Y: 3
X: 3 Y: 1

as expected.

Upvotes: 4

Cary Swoveland
Cary Swoveland

Reputation: 110745

You could make use of the Matrix class.

require 'matrix'

def evaluate(array)  
  Matrix[*array].each_with_index { |e,x,y| puts "X: #{x} Y: #{y}" if e == 1 }
end

evaluate(array)
X: 0 Y: 0
X: 1 Y: 1
X: 2 Y: 0
X: 2 Y: 3
X: 3 Y: 1

Upvotes: 1

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