I have an array like this:
["b3", "a3", "a5", "b2"]
and I need to get it to this:
[["b3", "b2"] ["a3", "a5"]]
I have tried various things including:
["b3", "a3", "a5", "b2"].map { |i| i.include? 'a' }
# => returns [false, true, true, false]
["b3", "a3", "a5", "b2"].detect { |i| i.include? 'a' }
# returns "a3"
Is there an simple way for this to be done?
Thanks
a = ["b3", "a3", "a5", "b2"]
a.group_by { |s| s[0] }.values
#=> [["b3", "b2"], ["a3", "a5"]]
Enumerable#group_by produces:
h = a.group_by { |s| s[0] }
#=> {"b"=>["b3", "b2"], "a"=>["a3", "a5"]}
and then we use Hash#values to extract the values:
h.values
#=> [["b3", "b2"], ["a3", "a5"]]
Before reading this answer @Cary's answer is optimised and best. But I think what you were trying to do is this
["b3", "a3", "a5", "b2"].select{|e| e.include?('a')}
=> ["a3", "a5"]
