Python | Convert string tuples to list tuples

Sometimes, while working with Python we can have a problem in which we have a list of records in form of tuples in stringified form and we desire to convert them to a list of tuples. This kind of problem can have its occurrence in the data science domain. Let's discuss certain ways in which this task can be performed. 

Method 1 (Using eval() + list comprehension): This problem can be easily performed as a one-liner using the inbuilt function of eval(), which performs this task of string to tuple conversion and list comprehension. 

The original list is : ["('gfg', 1)", "('is', 2)", "('best', 3)"]
The list tuple after conversion : [('gfg', 1), ('is', 2), ('best', 3)]

Time complexity: O(n), where n is the length of the input list.
Auxiliary space: O(n), as we are creating a new list with the same length as the input list.

Method 2 (Using eval() + map()): This task can also be performed using a combination of the above functions. The task performed by list comprehension above can be performed using a map() in this method. 

The original list is : ["('gfg', 1)", "('is', 2)", "('best', 3)"]
The list tuple after conversion : [('gfg', 1), ('is', 2), ('best', 3)]

Time Complexity: O(n), where n is the number of elements in the input list.
Auxiliary Space: O(n), where n is the number of elements in the input list, for the output list.

Method 3: Using the enumerate function

[('gfg', 1), ('is', 2), ('best', 3)]

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

Method 4: Using map()+eval()

[('gfg', 1), ('is', 2), ('best', 3)]

The time complexity of the program is O(n), where n is the length of the list "s".
The auxiliary space complexity of the program is also O(n), as the list "x" has to store n elements, where n is the length of the input list "s".

Method#5: Using Regex method.

The original list is : ["('gfg', 1)", "('is', 2)", "('best', 3)"]
The list tuple after conversion : [('gfg', 1), ('is', 2), ('best', 3)]

Time Complexity: O(n)
Auxiliary Space: O(n)

Method 6: (Using ast.literal_eval() instead of eval())

The ast module provides a safer way to evaluate string literals. The ast.literal_eval() function can evaluate a string containing a Python expression or a container object literal and return the corresponding object. It only evaluates literals, so it won't execute arbitrary code like eval().

The original list is : ["('gfg', 1)", "('is', 2)", "('best', 3)"]
The list tuple after conversion : [('gfg', 1), ('is', 2), ('best', 3)]

Time Complexity: O(n)
Auxiliary Space: O(n)