Pandas pivot table fill_value parameter throws warning

Python Help
1

Hi Everyone,

I have a pandas dataframe with set of columns and rows and using pivot table function creating a table out of it. I am setting fill_value parameter to ‘NULL’ to replace NAN with NUL values.
This piece of code does not throws any errors/warning in older version, but for pandas 2.2.2 version it throws below warning

’ Downcasting object dtype arrays on .fillna, .ffill, .bfill is deprecated and will change in a future version. Call result.infer_objects(copy=False) instead. To opt-in to the future behavior, set pd.set_option('future.no_silent_downcasting', True)’

I have gone through some blogs and documentation but could not find out a proper page where it explains the reason why it throws this warning and fix to implement it.

As per suggestion in warngin, setting result.infer_objects(copy=False) did not work in my case, it still throws error.
Setting “pd.set_option(‘future.no_silent_downcasting’, True)” property stop showing this warning and I do not see any difference in output data as well.However I do not want to implement this until I have a proper understanding of what it does and what is the good solution to avid getting this warning.

Point to note here, removing fill_value parameter does not show this warning.

Can anyone please help to understand on this issue and fix for this?

2

What are the column dtypes (of the resulting pivot table) when you don’t specify the fill_value parameter? My suspicion is that they are floats, and so when you are specifying a string as the fill value, it would have to downcast to object dtype (leading to that message)