Python | Shift sublist in list

Last Updated : 27 Aug, 2019

Sometimes, while working with list, we can have a problem in which we need to shift some sublist to desired index in same sublist. This problem can occur in day-day programming. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using insert() + pop() + loop
The combination of above functions can be used to perform the particular task. The pop function can be used to remove the sublist and insert function inserts the sublist. This happens for each element in single iteration in loop.

# Python3 code to demonstrate working of
# Shift sublist in list
# Using insert() + pop() + loop
  
# function to perform the task 
def shift_sublist(test_list, strt_idx, no_ele, shft_idx):
    for ele in range(no_ele):
        test_list.insert(shft_idx + 1, test_list.pop(strt_idx))
    return test_list
  
# initializing list
test_list = [4, 5, 6, 7, 3, 8, 10, 1, 12, 15, 16]
  
# printing original list
print("The original list is : " +  str(test_list))
  
# Using insert() + pop() + loop
# Shift sublist in list
res = shift_sublist(test_list, 2, 3, 6)
  
# Printing result
print("The list after shift of sublist : " +  str(res))

Output :

The original list is : [4, 5, 6, 7, 3, 8, 10, 1, 12, 15, 16]
The list after shift of sublist : [4, 5, 8, 10, 1, 6, 7, 3, 12, 15, 16]

Method #2 : Using list slicing
This task can also be using list slicing technique in which one can just add the different sections of list at required positions.

# Python3 code to demonstrate working of
# Shift sublist in list
# Using list slicing
  
# function to perform the task 
def shift_sublist(test_list, strt_idx, no_ele, shft_idx):
    return (test_list[:strt_idx] + test_list[strt_idx + no_ele : no_ele + shft_idx - 1]
            + test_list[strt_idx : strt_idx + no_ele] + test_list[shft_idx + no_ele -1:])
  
# initializing list
test_list = [4, 5, 6, 7, 3, 8, 10, 1, 12, 15, 16]
  
# printing original list
print("The original list is : " +  str(test_list))
  
# Using list slicing
# Shift sublist in list
res = shift_sublist(test_list, 2, 3, 6)
  
# Printing result
print("The list after shift of sublist : " +  str(res))

Output :

The original list is : [4, 5, 6, 7, 3, 8, 10, 1, 12, 15, 16]
The list after shift of sublist : [4, 5, 8, 10, 1, 6, 7, 3, 12, 15, 16]

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