How to transform an index into a column in Python?

Question

I am struggling with the following: I have on dataset and have transposed it. After transposing, the first column was set as an index automatically, and from now one, this "index" column is not recognized as a variable. Here is an example of what I mean;

df =     Date     A B C
       1/1/2021   1 2 3
       1/2/2021   4 5 6

input:   df_T = df.t
output:  index 1/1/2021 1/2/2021 
           A        1      4
           B        2      5
           C        3      6

I would like to have a variable, and name if it is possible, instead of the generated "index".

Generally, one can reset the index which will make it a column df.reset_index(inplace=True). I think that's what you're looking for. — sophocles
– sophocles, Commented Dec 19, 2021 at 17:36

Fariman Guliev · Accepted Answer · 2021-12-19 18:00:20Z

1

To reproduce this dataset, I have used this chunk of code:

data = [['1/1/2021', 1, 2, 3], ['3/1/2021', 4, 5, 6]]
df = pd.DataFrame(data)
df.columns = ['Date', 'A', 'B', 'C']
df.set_index('Date', inplace=True)

To have meaningfull column inplace of index, the next line can be run:

df_T = df.T.reset_index()

To rename the column 'index', method rename can be used:

df_T.rename(columns={'index':'Variable'})

answered Dec 19, 2021 at 18:00

Fariman Guliev

511 silver badge5 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

user23952 · Accepted Answer · 2021-12-19 18:03:17Z

A Pandas Data Frame typically has names both for the colmns and for the rows. The list of names for the rows is called the "Index". When you do a transpose, rows and columns switch places. In your case, the dates column is for some reason the index, so it becomes the column names for the new data frame. You need to create a new index and turn the "Date" column into a regular column. As @sophocies wrote above, this is achived with df.reset_index(...). I hope the code example below will be helpful.

import pandas as pd
df = pd.DataFrame(columns=['Date', 'A', 'B', 'C'], data=[['1/1/2021', 1, 2,3], ['1/2/2021', 4,5,6]])
df.set_index('Date', inplace=True)
print(df.transpose(copy=True))
#Recreated the problem
df.reset_index(inplace=True)
print(df.transpose())

Output

	0	1
Date	1/1/2021	1/2/2021
A	1	4
B	2	5
C	3	6

I hope this is what you wanted!

Collectives™ on Stack Overflow

How to transform an index into a column in Python?

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related