python - Swap slices of indexes using a function

Question

Follow-up question of: Python swap indexes using slices

r = ['1', '2', '3', '4', '5', '6', '7', '8'] 

If I want to swap slices, using a function, what would be the correct method?

def swap(from,to):
  r[a:b+1], r[c+1:d] = r[c:d], r[a:b]

swap(a:b,c:d)

I want to swap the numbers 3 + 4 with 5 + 6 + 7 in r:

swap(2:4,4:7)

Is this correct?

Answer 1

Without any calculation, you can do :

def swap(r,a,b,c,d):
   assert a<=b<=c<=d  
   r[a:d]=r[c:d]+r[b:c]+r[a:b]