A string (thats looks like an array) into an array Ruby

Question

I have an output from an API that look like this... (its a string)

[[2121212,212121,asd],[2323232,23232323,qasdasd]]

Its a string - not an array. I want to convert it to an array and then extract the first two elements in each array in the nested array to:

[2121212,212121],[2323232,23232323]

What's the best way to do this ruby? I could use regexp and extract - but basically the string is already an array, however the class is a string.

I tried

array.push(response)

but that just put the string in to the array as one element. I guess what would be nice is a to_array method

possible duplicate of Ruby: Parsing a string representation of nested arrays into an Array? — Mischa
– Mischa, Commented Apr 23, 2012 at 9:32
This is not the same - neither JSON nor eval will handle strings without quotation marks. If the strings are so simple as asd, I'd just added quotations marks to them by regexp and then used JSON.parse or eval: eval str.gsub(/([a-zA-Z]+)/, '"\1"') — Lukas Stejskal
– Lukas Stejskal, Commented Apr 23, 2012 at 9:37
Lukas - sorry the strings will change - they will always be syntactically the same ie [element, element,element] I could call a .to_json method on it and have it return as "[element, element, element'] — Charlie Davies
– Charlie Davies, Commented Apr 23, 2012 at 9:41

peter · Accepted Answer · 2012-04-23 12:51:55Z

2

You will need to use regular expression anyway if not eval (shrudder...), this is the shortest one

str = "[[2121212,212121,asd],[2323232,23232323,qasdasd],[2424242,24242424,qasdasd]]"
p str.scan(/(\d+),(\d+)/)

=>[["2121212", "212121"], ["2323232", "23232323"], ["2424242", "24242424"]]

answered Apr 23, 2012 at 12:51

peter

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Comments

Patrick Oscity · Accepted Answer · 2012-04-23 13:01:42Z

0

Assuming this is a JSON response (and if so, it is badly malformed and you should talk to the people that are responsible for this) you could write something like:

require 'json'

input= '[[2121212,212121,Asd],[2323232,23232323,qasdasd]]'
input.gsub!(/([A-Za-z ]+)/,'"\1"')
json = JSON.parse input
output = json.map{|x| x[0...2]}
p output

this prints

[[2121212, 212121], [2323232, 23232323]]

answered Apr 23, 2012 at 13:01

Patrick Oscity

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1 Comment

Patrick Oscity Over a year ago

if your code also parses valid json, you should improve the regex in such a manner that it will not quote already quoted strings, though. but i'll leave that up to you :)

Soundar Rathinasamy · Accepted Answer · 2012-04-23 10:08:20Z

0

Using eval is very bad but I have no other easy option.

test_str = "[[2121212,212121,asd],[2323232,23232323,qasdasd]]"
test_str.gsub!(/([a-z]+)/) do
  "'#{$1}'" 
 end
 => "[[2121212,212121,'asd'],[2323232,23232323,'qasdasd']]"
test_array = eval(test_str)
 => [[2121212, 212121, "asd"], [2323232, 23232323, "qasdasd"]]
test_array.each do |element|
  element.delete(element.last)
end
 => [[2121212, 212121], [2323232, 23232323]]

answered Apr 23, 2012 at 10:08

Soundar Rathinasamy

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3 Comments

d11wtq Over a year ago

You definitely has other options than eval. Namely JSON.parse. Also, your gsub can be written without the block: str.gsub!(/([a-z]+)/', '"\\1"').

Soundar Rathinasamy Over a year ago

Thanks for your suggestion but JSON.parse("[[2121212,212121,asd],[2323232,23232323,qasdasd]]") JSON::ParserError: 399: unexpected token at 'asd],[2323232,23232323,qasdasd]]'

Asherah Over a year ago

@soundar: but the thing you are evalling could be just as easily JSON.parsed if you only changed the line "'#{$1}'" to "\"#$1\"". You would then produce something like '[[21212,212,"asd"],…]', which is valid JSON.

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