Convert a String Containing an Array to an Array in Ruby

Question

I have a string that contains an array that i would like to convert into an array. How would you do this?

I want to convert this:

myvar=
"[[Date.UTC(2010, 0, 23),0],[Date.UTC(2010, 0, 24),0],[Date.UTC(2010, 0, 25),3],[Date.UTC(2010, 0, 26),0],[Date.UTC(2010, 0, 27),0],[Date.UTC(2010, 0, 28),0],[Date.UTC(2010, 0, 29),0],[Date.UTC(2010, 0, 30),0],[Date.UTC(2010, 0, 31),0],[Date.UTC(2010, 1, 01),0],[Date.UTC(2010, 1, 02),0],[Date.UTC(2010, 1, 03),1],[Date.UTC(2010, 1, 04),2],[Date.UTC(2010, 1, 05),0],[Date.UTC(2010, 1, 06),0],[Date.UTC(2010, 1, 07),0],[Date.UTC(2010, 1, 08),0],[Date.UTC(2010, 1, 09),0],[Date.UTC(2010, 1, 10),0],[Date.UTC(2010, 1, 11),0],[Date.UTC(2010, 1, 12),0],[Date.UTC(2010, 1, 13),0],[Date.UTC(2010, 1, 14),0],[Date.UTC(2010, 1, 15),0],[Date.UTC(2010, 1, 16),0],[Date.UTC(2010, 1, 17),0],[Date.UTC(2010, 1, 18),0],[Date.UTC(2010, 1, 19),0],[Date.UTC(2010, 1, 20),0],[Date.UTC(2010, 1, 21),0]]"
myvar.class
>>string

Into This:

myvar = 
[[Date.UTC(2010, 0, 23),0],[Date.UTC(2010, 0, 24),0],[Date.UTC(2010, 0, 25),3],[Date.UTC(2010, 0, 26),0],[Date.UTC(2010, 0, 27),0],[Date.UTC(2010, 0, 28),0],[Date.UTC(2010, 0, 29),0],[Date.UTC(2010, 0, 30),0],[Date.UTC(2010, 0, 31),0],[Date.UTC(2010, 1, 01),0],[Date.UTC(2010, 1, 02),0],[Date.UTC(2010, 1, 03),1],[Date.UTC(2010, 1, 04),2],[Date.UTC(2010, 1, 05),0],[Date.UTC(2010, 1, 06),0],[Date.UTC(2010, 1, 07),0],[Date.UTC(2010, 1, 08),0],[Date.UTC(2010, 1, 09),0],[Date.UTC(2010, 1, 10),0],[Date.UTC(2010, 1, 11),0],[Date.UTC(2010, 1, 12),0],[Date.UTC(2010, 1, 13),0],[Date.UTC(2010, 1, 14),0],[Date.UTC(2010, 1, 15),0],[Date.UTC(2010, 1, 16),0],[Date.UTC(2010, 1, 17),0],[Date.UTC(2010, 1, 18),0],[Date.UTC(2010, 1, 19),0],[Date.UTC(2010, 1, 20),0],[Date.UTC(2010, 1, 21),0]]
myvar.class
>>Array

Peter · Accepted Answer · 2010-02-22 04:45:59Z

2

While the obvious answer involves eval, this is dangerous. I would instead recommend parsing it. Since this is quite a well defined data format (it seems), you can use this:

myvar.scan(/\d+/).map(&:to_i).each_slice(4).map{|*x,y| [Date.UTC(*x), y]}

this will

pull out all the digits
convert them to integers
separate them into groups of four
apply the first three of each group to Date.UTC as the first through third arguments
pair each date with its corresponding y
create an array containing all of these pairs.

I don't have a Date.UTC method, but I assume you have some custom method called that.

answered Feb 22, 2010 at 4:45

Peter

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1 Comment

Schneems Over a year ago

Hmm...so Date.UTC is actually a javascript function that i'm trying to embed in the html, and not a function in Ruby. Your solution is technically correct, though provides an error because ruby has no date.utc. Oh well... thanks for the info, i'll likely use it later.

Bank · Accepted Answer · 2010-02-22 05:02:37Z

0

try eval command

x = eval("[\"foo\",\"bar\",\"land\"]")

=> ["foo", "bar", "land"]

x

=> ["foo", "bar", "land"]

but eval is danger be care full when use it.

answered Feb 22, 2010 at 5:02

Bank

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