Add column to the end of Pandas DataFrame containing average of previous data

Question

I have a DataFrame ave_data that contains the following:

ave_data

Time        F7           F8            F9  
00:00:00    43.005593    -56.509746           


        

Answer 1

df.assign is specifically for this purpose. It returns a copy to avoid changing the original dataframe and/or raising SettingWithCopyWarning. It works as follows:

data_with_ave = ave_data.assign(average = ave_data.mean(axis=1, numeric_only=True))

This function can also create multiple columns at the same time:

data_with_ave = ave_data.assign(
                    average = ave_data.mean(axis=1, numeric_only=True),
                    median = ave_data.median(axis=1, numeric_only=True)
)

As of pandas 0.36, you can even reference a column just created to create another:

data_with_ave = ave_data.assign(
                    average = ave_data.mean(axis=1, numeric_only=True),
                    isLarge = lambda df: df['average'] > 10
)