Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

Appearance settings

BUG: when using id_vars in .melt(), the id_vars does not recognize the column name in a multiIndex dataframe #60018

Copy link
Copy link
Open
@ivan-marroquin

Description

@ivan-marroquin
Issue body actions

Pandas version checks

  • I have checked that this issue has not already been reported.

  • I have confirmed this bug exists on the latest version of pandas.

  • I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd
import yfinance as yf
from datetime import date, timedelta

end_date= date.today().strftime("%Y-%m-%d")
start_date= (date.today() - timedelta(days= 365)).strftime("%Y-%m-%d")

tickers= ['RELIANCE.NS', 'TCS.NS', 'INFY.NS', 'HDFCBANK.NS']

data= yf.download(tickers, start= start_date, end= end_date)

data= data.reset_index()

data_melted= data.melt(id_vars= ['Date'], var_name= ['Attribute', 'Ticker'])

Issue Description

KeyError Traceback (most recent call last)
Cell In [19], line 15
11 data= data.reset_index()
13 # melt the DataFrame to make it long format where each row is a
14 # unique combination of Date, Ticker, and attributes
---> 15 data_melted= data.melt(id_vars= ['Date'], var_name= ['Attribute', 'Ticker'])
17 # pivot the melted DataFrame to have the attributes (Open, High, Low, etc.) as columns
18 data_pivoted= data_melted.pivot_table(index= ['Date', 'Ticker'],
19 columns= 'Attribute', values= 'value',
20 aggfunc= 'first')

File ~/python_3.9.0/lib/python3.9/site-packages/pandas/core/frame.py:9942, in DataFrame.melt(self, id_vars, value_vars, var_name, value_name, col_level, ignore_index)
9932 @appender(_shared_docs["melt"] % {"caller": "df.melt(", "other": "melt"})
9933 def melt(
9934 self,
(...)
9940 ignore_index: bool = True,
9941 ) -> DataFrame:
-> 9942 return melt(
9943 self,
9944 id_vars=id_vars,
9945 value_vars=value_vars,
9946 var_name=var_name,
9947 value_name=value_name,
...
77 )
78 if value_vars_was_not_none:
79 frame = frame.iloc[:, algos.unique(idx)]

KeyError: "The following id_vars or value_vars are not present in the DataFrame: ['Date']"

Expected Behavior

The melt function should generate a DataFrame to make it long format where each row is a unique combination of Date, Ticker, and attributes

Installed Versions

INSTALLED VERSIONS ------------------ commit : d9cdd2e python : 3.9.0.final.0 python-bits : 64 OS : Linux OS-release : 6.5.0-25-generic Version : #25~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Feb 20 16:09:15 UTC 2 machine : x86_64 processor : x86_64 byteorder : little LC_ALL : None LANG : en_US.UTF-8 LOCALE : en_US.UTF-8

pandas : 2.2.2
numpy : 1.23.3
pytz : 2024.2
dateutil : 2.8.2
setuptools : 59.8.0
pip : 22.3.1
Cython : 0.29.32
pytest : None
hypothesis : None
sphinx : 5.1.1
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.9.1
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 3.1.2
IPython : 8.5.0
pandas_datareader : None
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : None
bottleneck : None
dataframe-api-compat : None
fastparquet : None
fsspec : 2024.6.1
gcsfs : None
matplotlib : None
numba : None
numexpr : 2.10.1
odfpy : None
openpyxl : 3.1.2
pandas_gbq : None
pyarrow : 16.1.0
pyreadstat : None
python-calamine : None
pyxlsb : None
s3fs : 2024.6.1
scipy : 1.13.1
sqlalchemy : 2.0.31
tables : None
tabulate : 0.9.0
xarray : 2024.6.0
xlrd : None
zstandard : None
tzdata : 2023.3
qtpy : None
pyqt5 : None

Python 3.9.0

Metadata

Metadata

Assignees

No one assigned

    Labels

    BugIndexRelated to the Index class or subclassesRelated to the Index class or subclassesNeeds DiscussionRequires discussion from core team before further actionRequires discussion from core team before further actionReshapingConcat, Merge/Join, Stack/Unstack, ExplodeConcat, Merge/Join, Stack/Unstack, Explode

    Type

    No type

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions

      Morty Proxy This is a proxified and sanitized view of the page, visit original site.