Python | Convert a list into tuple of lists

We are given a list, the task is to convert the list into tuple of lists.

Input: ['Geeks', 'For', 'geeks']
Output: (['Geeks'], ['For'], ['geeks'])

Input: ['first', 'second', 'third']
Output: (['first'], ['second'], ['third'])

Method #1: Using Comprehension 

Python3

# Python code to convert a list into tuple of lists

# Initialisation of list
Input = ['Geeks', 'for', 'geeks']

# Using list Comprehension
Output = tuple([name] for name in Input)

# printing output
print(Output)

Output:

(['Geeks'], ['for'], ['geeks'])

Time Complexity: O(n), where n is the length of the Input list.
Auxiliary Space: O(n), as we are creating a new tuple of lists of the same length as Input.

Method #2 : Using Map + Lambda 

Python3

# Python code to convert a list into tuple of lists

# Initialisation of list
Input = ['first', 'second', 'third']

# Using map + lambda
Output = tuple(map(lambda x: [x], Input))

# printing output
print(Output)

Output:

(['first'], ['second'], ['third'])

Time complexity: O(n), where n is the length of the input list.
Auxiliary space: O(n), where n is the length of the input list.

Method #3 : Using Map + zip 

Python3

# Python code to convert a list into tuple of lists

# Initialisation of list
Input = ['first', 'second', 'third']

# Using Map + zip
Output = tuple(map(list, zip(Input)))

# printing output
print(Output)

Output:

(['first'], ['second'], ['third'])

Method #4: Using enumerate function 

Python3

lst = ['Geeks', 'for', 'geeks']
x = tuple([i] for a,i in enumerate(lst))
print(x)

Output

(['Geeks'], ['for'], ['geeks'])

Method#5: Using Recursive method.

Algorithm:

1. Define a recursive function list_to_tuple_of_lists which takes a list lst as an input.
2. If the list is empty, return an empty tuple.
3. Otherwise, take the first element of the list and wrap it in a list.
4. Wrap that list in a tuple, and concatenate the tuple with the result of recursively calling list_to_tuple_of_lists on the rest of the list.
5. Return the resulting tuple.

Python3

def list_to_tuple_of_lists(lst):
    if not lst:
        return ()
    else:
        return ([lst[0]],) + list_to_tuple_of_lists(lst[1:])


# example usage
input_list = ['Geeks', 'for', 'geeks']
output_tuple = list_to_tuple_of_lists(input_list)
print(output_tuple)  # output: (['Geeks'], ['for'], ['geeks'])

Output

(['Geeks'], ['for'], ['geeks'])

Time Complexity:
The time complexity of the list_to_tuple_of_lists function is O(n), where n is the length of the input list. This is because the function makes a recursive call on a list of length n-1, and performs constant time operations (creating a list and wrapping it in a tuple) for each element of the list.

Auxiliary Space:
The space complexity of the list_to_tuple_of_lists function is also O(n), where n is the length of the input list. This is because the function creates a new list of length 1 for each element of the input list, and the maximum depth of the recursion is also n.

Method #6: Using a For Loop

Step-by-step approach:

• Initialize an empty list result to store the output.
• Use a for loop to iterate over each element of the input list.
• Append each element as a single-element list to the result list.
• Convert the result list to a tuple using the tuple() function.
• Assign the tuple to the output variable.
• Print the output variable.

Python3

# Python code to convert a list into tuple of lists

# Initialization of list
input_list = ['Geeks', 'for', 'geeks']

# Using a for loop
result = []
for name in input_list:
    result.append([name])

# Convert result list to tuple
output = tuple(result)

# Print output
print(output)

Output

(['Geeks'], ['for'], ['geeks'])

Time complexity: O(n), where n is the number of elements in the input list, because we iterate over each element of the list once.
Auxiliary space: O(n), where n is the number of elements in the input list, because we create a list of n lists to store the output before converting it to a tuple.