Reposition an element in an Array

Question

Say I have...

arr = ["a", "b", "c"]

...and I want to move "a" between "b" and "c". I currently do

arr.delete("a")
arr.insert(2, "a")

Can I do that in a single operation?

Thanks

Answer 1

You can use parallel assignment:

arr[0], arr[1] = arr[1], arr[0]
=> ["b", "a"]
arr
=> ["b", "a", "c"]

Answer 2

You don't need to repeat "a". Put them in one:

arr.insert(2, arr.delete("a"))

Answer 3

If you want to move "a" between "b" and "c", then you should do:

arr.insert(1, arr.delete_at(0))

※Use .delete_at instead of .delete because you may have multiple 'a' in your array.

Answer 4

Use Array#shuffle!

arr = [ "a","b","c" ] 
arr.shuffle! until arr[1] == 'a' && arr[0]=='b'
p arr #=> ["b", "a", "c"]

Answer 5

Insert a after b, regardless of where they are in the array:

arr.insert(arr.index("b"), arr.delete_at(arr.index("a")))
=> ["b", "a", "c"]

You could also do:

 arr[arr.index("a")], arr[arr.index("b")] = "b","a"