I have 5 lists containing data: List_1, List_2, List_3, List_4, List_5

I want to perform an analysis to each of these lists, but also keep the original lists as a reference for later so I can compare them. This is relatively easy to do since I only have 5 lists:

New_list_1 = List_1
New_list_2 = List_2
New_list_3 = List_3
New_list_4 = List_4
New_list_5 = List_5

I am aware that I could also make like a "list of lists" List = [List_1, List_2, List_3...] but then I would still have the problem of having to do, which is not shorter:

New_list_1 = List[0]
New_list_2 = List[1]
New_list_3 = List[2]
New_list_4 = List[3]
New_list_5 = List[4]

But for future, what if I had like 700 lists? Would it be possible to loop over these numbered lists like this?

for i in range(700):
    New_list_*insert i here somehow* = List_*insert i here somehow*

If this approach is possible, how would I go about attaching i, which is an integer, as string, to a variable name?

I have 5 lists containing data: List_1, List_2, List_3, List_4, List_5

I want to perform an analysis to each of these lists, but also keep the original lists as a reference for later so I can compare them. This is relatively easy to do since I only have 5 lists:

New_list_1 = List_1
New_list_2 = List_2
New_list_3 = List_3
New_list_4 = List_4
New_list_5 = List_5

I am aware that I could also make like a "list of lists" List = [List_1, List_2, List_3...] but then I would still have the problem of having to do, which is not shorter:

New_list_1 = List[0]
New_list_2 = List[1]
New_list_3 = List[2]
New_list_4 = List[3]
New_list_5 = List[4]

But for future, what if I had like 700 lists? Would it be possible to loop over these numbered lists like this?

for i in range(700):
    New_list_*insert i here somehow* = List_*insert i here somehow*

If this approach is possible, how would I go about attaching i, which is an integer, as string, to a variable name?

• python
• list
• loops
• variables
• number-formatting

• 3 Why do you need New_list_1? Why can't you just do New_lists = Lists[:]? If you have a number at the end of your variable name you are most likely making a mistake – mousetail Commented Nov 18, 2024 at 11:00
• 1 None of the examples you showed make a copy of the lists. You just have the same list with two different names. – Mark Commented Nov 18, 2024 at 11:24
• 2 This may be an xy problem. Are you sure you can’t do the analysis you need without mutating the original lists? – Mark Commented Nov 18, 2024 at 11:26

3 Answers 3

If Lists is a list of lists then, to make a copy, you could do this:

Lists = [List_1, List_2, List_3, List_4, List_5]
New_lists = [e.copy() for e in Lists]

Note that a list's copy() function is shallow

• Instead of creating individual variables like New_list_1, New_list_2, etc., you can use a dictionary to store the lists. This allows you to map each list dynamically to a key, where the key can be the list number (e.g., 1, 2, ..., 700), and you can access or modify them easily.

# Example of original lists (List_1, List_2, ..., List_5)

    List_1 = [1, 2, 3]
    List_2 = [4, 5, 6]
    List_3 = [7, 8, 9]
    List_4 = [10, 11, 12]
    List_5 = [13, 14, 15]
    
    # Put your original lists in a dictionary
    
    lists = {
        1: List_1,
        2: List_2,
        3: List_3,
        4: List_4,
        5: List_5
    }
    
     # If you have more lists, you can extend this dynamically or use a loop
     # For example, simulating 700 lists (as an example)
    
        for i in range(1, 701):    
            lists[f"New_list_{i}"] = lists[i].copy()
    
         print(lists['New_list_1'])

Here is your answer use this function and give the required value then it is gonna search for all of the lists in that namespace to create a copy of it.

def copy_all_lists(namespace):
    """
    Finds all lists in the given namespace (e.g., globals() or locals()),
    creates a copy of each list, and assigns the copy to a new variable 
    with the name `copy_<original_list_name>`.
    
    Args:
        namespace (dict): The namespace to search for lists (e.g., globals(), locals()).
    """
    for name, value in namespace.items():
        if isinstance(value, list):
            # Create a copy of the list
            namespace[f'copy_{name}'] = value.copy()

Here is an example of using this function

# Example usage
my_list = [1, 2, 3]
another_list = ['a', 'b', 'c']

print("Before copying:", globals())

# Call the function with globals() or locals() as the namespace
copy_all_lists(globals())

print("After copying:", globals())