pandas - how can I group column by date and get the average from the other column in python?

Question

From the dataframe below:

I would like to group column 'datum' by date 01-01-2019 and so on. and get an average at the same time on column 'PM10_gemiddelde'.

So now all 01-01-2019 (24 times) is on hour base and i need it combined to 1 and get the average on column ' PM10_gemiddelde' at the same time. See picture for the data.

besides that, PM10_gemiddelde has also negative data. How can i erase that data in python easily?

Thank you! ps. im new with python

Answer 1

What you are trying to do can be achieve by:

data[['datum','PM10_gemiddelde']].loc[data['PM10_gemiddelde'] > 0 ].groupby(['datum']).mean()