How can I create duplicate dataframes from list of existing dataframes Python?

Question

Task

Create a set of duplicate dataframes with a different set of names, such as item28, item30, item31...item38.
After creating the new copies, I then have to modify the contents of specific columns.

Current Process

Step 1: Create new dataframes by copying the original:

item28 = item1.copy(); 
item29 = item2.copy(); 
item30 = item3.copy(); 
item31 = item4.copy(); 
item32 = item5.copy(); 
item33 = item6.copy(); 
item34 = item7.copy(); 
item35 = item8.copy(); 
item36 = item9.copy(); 
item37 = item10.copy(); 
item38 = item11.copy();

Step 2. Modify the columns in the new data frame: item28['indicator_number'] = 28;

Goal

Reproduce this manual process in a dynamic, Pythonic way.

if you call id(item1) and id(item28) do they give you the same number for both dataframes? — Lucas Roberts
– Lucas Roberts, Commented Apr 6, 2022 at 22:20
Your "duplicates" are only references to the originals, not standalone copies. If you modify a "duplicate", you're going to see that modification in the original. What are you trying to do here? — ddejohn
– ddejohn, Commented Apr 6, 2022 at 22:26
how are the variables generated? feel like a simple refactor upstream could help you more — Umar.H
– Umar.H, Commented Apr 6, 2022 at 22:26
This statement doesn't make sense: "These dataframes are created elsewhere in the program and have to be duplicated after the fact, otherwise, I would create a copy" -- you can create a copy at any time. — ddejohn
– ddejohn, Commented Apr 6, 2022 at 22:31

Nimantha · Accepted Answer · 2025-05-19 15:11:37Z

1

The "Pythonic" way to generate your duplicates:

list_of_copies = [df.copy() for df in list_of_originals]

Note the use of .copy() -- this is necessary because otherwise you're just creating duplicate references to the same dataframes. Any change made in the "duplicate" would be reflected in the original which is almost certainly not what you want (otherwise what would be the point?).

If you similarly have a list of values you want to use to update the dataframe copies:

for new_value, df in zip(list_of_values, list_of_copies):
    df["indicator_number"] = new_value

edited May 19 at 15:11

Nimantha

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answered Apr 6, 2022 at 22:31

ddejohn

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2 Comments

ddejohn Over a year ago

@oda deep defaults to True

OTheDev Over a year ago

Apologies, I only skimmed the answer and realized after-the-fact that you were applying the copy method of a df as opposed to a list.

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