How to add sub-headers to the pandas Dataframe in the loop in python?

Question

I have the empty data frame, with the header of the Data frame indicating the groups. Example,

df = pd.DataFrame(columns=['group1', 'group2', 'group3', 'group4', 'group5', 'group6'])

Now, I want add the sub-headers to each empty column in loop, because the original data frame is long. I have tried the code given below,

for ii in range(len(df.columns)):
    df.columns[ii] = pd.MultiIndex.from_product([[ii],['condition_1','condition_2']])

The error I am getting is 'Index does not support mutable operations'. The expected output is,

group1		group2		group3		group4		group5		group6
condition_1	condition_2	condition_1	condition_2	condition_1	condition_2	condition_1	condition_2	condition_1	condition_2	condition_1	condition_2

How can I add the sub-headers (condition_1 and condition_2) to the to the pandas Data frame in the loop in python?

Thank you.

you want to have condition1 and condition2 for every group1 to group6 right? you double the columns from 6 to 12 columns with that IIUC. — Rabinzel
– Rabinzel, Commented May 20, 2022 at 11:32
I don't really understand your objective, can you post the output. I think it is easier for everyone to figure out — PTQuoc
– PTQuoc, Commented May 20, 2022 at 11:57
Do you want pd.DataFrame(columns=pd.MultiIndex.from_product([df.columns, ['condition_1','condition_2']]))? — mozway
– mozway, Commented May 20, 2022 at 12:34
@Vedant why do you need a loop? This is already using all the columns! Try it — mozway
– mozway, Commented May 20, 2022 at 12:44

Code Different · Accepted Answer · 2022-05-20 19:35:33Z

1

groups = [f"group{i+1}" for i in range(6)]
conditions = [f"condition{i+1}" for i in range(2)]

df = pd.DataFrame(columns=pd.MultiIndex.from_product([groups, conditions]))

answered May 20, 2022 at 19:35

Code Different

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