How to delete quotation marks in an array in Ruby

Question

I am working on Test First Ruby with rspec examples testing...

which I need to pass this test.

it "tokenizes a string" do
    calculator.tokens("1 2 3 * + 4 5 - /").should ==
      [1, 2, 3, :*, :+, 4, 5, :-, :/]
  end

And here is my code

def tokens(str)
    data = str.split(' ')
    outcomes = []
    data.collect do |x|
      if x.to_i != 0
        outcomes.push(x.to_i)
      elsif x.to_i == 0
        temp = x.gsub('"', '')
        outcomes.push(":#{temp}")
      end
    end
    outcomes
  end

However, I got these feedback. Have no idea how to get rid of the quotation mark.

Failure/Error: [1, 2, 3, :*, :+, 4, 5, :-, :/]                                                                                                                               
       expected: [1, 2, 3, :*, :+, 4, 5, :-, :/]                                                                                                                                  
            got: [1, 2, 3, ":*", ":+", 4, 5, ":-", ":/"] (using ==)

By the way, your code has a bug: you cannot enter a `0`. – Jörg W Mittag Nov 14 '14 at 11:44 — Jörg W Mittag, Nov 14 '14 at 11:44

score 3 · Answer 1 · edited Nov 14 '14 at 09:47

3

The problem are not the quotation marks. Quotes mean that the element is a String type, your spec expects a Symbol.

outcomes.push(":#{temp}")

should be

outcomes.push(temp.to_sym)

To give you an idea

2.1.2 :006 > :*.class
 => Symbol 
2.1.2 :007 > ":*".class
 => String

edited Nov 14 '14 at 09:47

Sergio Tulentsev

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answered Nov 14 '14 at 09:36

Simone Carletti

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actually just `temp.to_sym` – Cristian Lupascu Nov 14 '14 at 09:37
I try to change it like this, but the result still the same, 'elsif x.to_i == 0 temp = x.to_sym outcomes.push(":#{temp}") end' – Yumiko Nov 14 '14 at 09:41
@SimoneCarletti got it figured out, thanks for your help – Yumiko Nov 14 '14 at 09:48
This should probably be `outcomes.push(x.to_sym)`. `temp = x.gsub('"', '')` was the OP's attempt to remove the quotes. – Stefan Nov 14 '14 at 10:23

Roman Kiselenko · Accepted Answer · 2014-11-14T10:01:29.693

3

Try this:

outcomes.push(:"#{temp}")

":#{temp}" is string but this :"#{temp}" symbol with string interpolation.

=>:"+".class
#> Symbol
=> ":+".class
#> String

edited Nov 14 '14 at 10:01

answered Nov 14 '14 at 09:45

Roman Kiselenko

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1

Thank you very much, it works now! Sorry I don't have enough reputation to vote you up yet :（ – Yumiko Nov 14 '14 at 09:47

score 2 · Answer 3 · edited May 23 '17 at 12:05

Simone Carletti already provided a solution for your problem (using to_sym), but you can further improve your code:

split(' ') can (in this case) be replaced with split (without arguments)
instead of elsif x.to_i == 0 you can use else
collect (or map) already creates and returns an array, you just have to provide the values

Applied to your code:

def tokens(str)
  str.split.map do |x|
    if x.to_i != 0
      x.to_i
    else
      x.to_sym
    end
  end
end

You can even write this in one line using a ternary if:

def tokens(str)
  str.split.map { |x| x.to_i != 0 ? x.to_i : x.to_sym }
end

You might have to modify your condition, since x.to_i != 0 returns false for x = "0".

How about `if x =~ /^[+-]?\d+$/` in place of `if x.to_i == 0` to squash the bug @JörgWMittag mentioned? Yumiko, in a real app, you also need to worry about bad data. For example, "9cats".to_i => 9`. — Cary Swoveland, Nov 14 '14 at 15:25

score 1 · Answer 4 · answered Nov 14 '14 at 09:57

1

":#{temp}" generates a String that starts with a colon.

But you want to translate your temp string to a symbol, like this temp.to_sym. Or you want to build a symbol like this: :"#{temp}" (note that the colon is in front of the string).

answered Nov 14 '14 at 09:57

spickermann

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How to delete quotation marks in an array in Ruby

4 Answers4

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