Adding items to a new array with index

Question

Trying to make a method skip_animals that takes an animals array and a skip integer and returns an array of all elements except first skip number of items.

input: skip_animals(['leopard', 'bear', 'fox', 'wolf'], 2)

expected output: ["2:fox", "3:wolf"]

   def skip_animals(animals, skip)
        arr = Array.new
        animals.each_with_index{|animal, index| arr.push("#{animal}:#{index}") }
        puts arr.drop(skip)
    end

This instead puts each output on a separate line and doesn't add them to the array arr. I thought the arr.push would add them correctly. What do I have to do to get the elements added to the array?

I want to use these methods, not map or something more advanced. I need to tinker with this each_with_index line, not overhaul it.

(This is a challenge on Hackerrank, so it uses STDIN and STDOUT)

EDIT

Here is my updated code with p instead of puts. It's giving me a weird output of two different arrays, not sure why.

def skip_animals(animals, skip)
    arr = Array.new
    animals.each_with_index{|animal, index| arr.push("#{index}:#{animal}") }
    p arr.drop(skip)
end

This gives me two lines of output:

["3:panda", "4:tiger", "5:deer"]
["0:leopard", "1:bear", "2:fox", "3:wolf", "4:dog", "5:cat"]

I'm assuming the top is the correct array, but I don't get why the second is printing also, or why it has a different set of animals.

Why can't you use map? I hope you are not going to say this is homework and you are trying to let someone else do the homework for you. — sawa
– sawa, Commented Jun 26, 2015 at 5:06
@sawa lol its an online problem on a learn to code site, not homework. So the goal is to learn why this isn't working. — Virge Assault
– Virge Assault, Commented Jun 26, 2015 at 5:08

falsetru · Accepted Answer · 2015-06-26 04:51:41Z

1

Use p instead of puts.

irb(main):001:0> puts ['1', '2']
1
2
=> nil
irb(main):002:0> p ['1', '2']
["1", "2"]

According to the documentation, puts:

Writes the given objects to ios as with IO#print. Writes a record separator (typically a newline) after any that do not already end with a newline sequence. If called with an array argument, writes each element on a new line. If called without arguments, outputs a single record separator.

BTW, I would code like this (using Enumerable#map + returning result instead of printing inside the function):

def skip_animals(animals, skip)
  animals.drop(skip).each_with_index.map { |animal, index|
    ("#{index + skip}:#{animal}")
  }
end

p skip_animals(['leopard', 'bear', 'fox', 'wolf'], 2)

edited Jun 26, 2015 at 4:51

answered Jun 26, 2015 at 4:45

falsetru

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4 Comments

Virge Assault Over a year ago

This did get an array printing, but something in the code is still wrong. Question edited above, any ideas?

falsetru Over a year ago

@VirgeAssault, "#{animal}:#{index}", index and animal should be swapped. Aren't they?, Check the last code in the answer.

Virge Assault Over a year ago

yes, but the error is bc I'm getting two lines of output for some reason. Can you check the edited code w/ output and see if you know why

falsetru Over a year ago

@VirgeAssault, I cannot reproduce the symptom you have. Is there any other call except skip_animals(['leopard', 'bear', 'fox', 'wolf'], 2)?

jon snow · Accepted Answer · 2015-06-26 04:48:29Z

0

just remove puts remove form this line puts arr.drop(skip)

def skip_animals(animals, skip)
    arr = Array.new
    animals.each_with_index{|animal, index| arr.push("#{animal}:#{index}") }
    arr.drop(skip)
end

answered Jun 26, 2015 at 4:48

jon snow

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1 Comment

Virge Assault Over a year ago

Without the puts nothing is put out. I think I need to use p instead, but not sure about the STDIN stuff from HackerRank? Any ideas?

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