The “AssertionError: Group argument must be None for now” error is typically encountered when using the pandas library in Python and indicates that the group argument of a function or method was not set to None. This error usually occurs when the function or method being called does not support grouping or aggregation of data.

For example, the pandas.DataFrame.sort_values() method is used to sort a DataFrame based on one or more columns. This method has a group parameter that can be used to specify a grouping criterion. If the group parameter is set to a value other than None, an AssertionError will be raised with the message “Group argument must be None for now”.

To avoid this error, simply ensure that the group parameter is set to None when calling the function or method in question. For example:

import pandas as pd

df = pd.read_csv("data.csv")

# Correct usage
df.sort_values(by=["col1", "col2"], group=None)

# Incorrect usage
df.sort_values(by=["col1", "col2"], group="col3") # AssertionError: Group argument must be None for now

It’s also worth noting that some functions or methods may not have a group parameter at all, in which case this error will not be encountered.