Ruby: Shorthand for a[1] || a[3] || a[6] ... ?

Question

I have a regular expression that returns multiple variables within a match. I am interested in the first non-null variable in a subset of indices within the match, so I am using

result = a[1] || a[3] || a[6] || ...

I would like to store the relevant indices in a configuration file along with the regular expression itself. What is the best shorthand notation that doesn't obfuscate the meaning?

Answer 1

Use values_at to get an array which contains only the elements at the specified indices. Then use find {|x| x} to get the first element that is not nil or false.

result = a.values_at(*indices).find {|x| x}

Answer 2

Another way:

result = [1,3,6].find {|x| a[x]}