title: how to create another dataframe from an existing one matching for multiple conditions
body: <p>I have a dataframe that has around 8 million rows for housing data having values for zip, year and month for over 3 years. I want to create 4 separate dataframes for each year from this one that has columns for zip and month wise prices. In short I want to search for a particular zip for year 2019's January month and add the average price in front of it in another dataframe.</p>