Saturday 15 October 2022

ValueError: cannot set a frame with no defined index and a scalar

This error message typically occurs when trying to assign a scalar value to a DataFrame without specifying the index or columns. Here's an example:

import pandas as pd df = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6]}) # This line will raise the ValueError df.loc[0] = 7

In this example, we have a DataFrame with two columns 'A' and 'B' and three rows. The df.loc[0] = 7 line is trying to set the first row of the DataFrame to the value 7. However, since we haven't specified which columns to update, Pandas is trying to set all columns to the scalar value 7, which isn't possible.

To fix this error, we need to specify which columns we want to update. For example:

df.loc[0, 'A'] = 7

This will set the value of the 'A' column in the first row to 7. Alternatively, we can specify the columns to update using a list:

df.loc[0, ['A', 'B']] = [7, 8]

This will set the values of both the 'A' and 'B' columns in the first row to 7 and 8, respectively.


  1. what to do if you get the error even if you specify the column? for example: df.loc[:, 'A'] = 7 . Thanks

    1. Share script and error details , will see