I wrote a loop script from an array like this:
a = [1, 2, 3, 4]
a.cycle.each{|i| p i; sleep 1}
And I want to start a loop from a specified index.
index = 2
(a[index..-1] + a.cycle).each{|i| p i; sleep 1}
This code ends up with error TypeError: no implicit conversion of Enumerator into Array.
How can I write a loop code like this case?
You could use rotate:
a.rotate(new_index).cycle { ... }
(NOTE: I don't think you need the .each)
rotate is the correct answer, but the reason your code wasn't working was because you were trying to concatenate the last part of the array and a.cycle, which is an Enumerator and probably not what you wanted. Furthermore, your code would output [3, 4, 1, 2, 3, 4] (if you fixed the other part) because you don't slice off the end when you concatenate the rest of the array.
Try this instead (actually, use rotate like @lurker said, but here's how to fix your original code):
(a[index..-1] + a[0...index]).cycle {|i| p i; sleep 1}
You could do it without Array#rotate. Suppose that for:
a = [1, 2, 3, 4]
the starting index were 2:
enum = a.cycle
2.times { enum.next }
enum.each { |i| p i; sleep 1 }
