Good morning,
I have a dataframe whose structure is given by
> head(citationsAllYears)
appln_id_cited appln_id_citn ano_prior
3 636 56755306 2008
4 636 644 2008
5 644 56755306 2008
6 1096 275471855 2007
7 1607 57977423 2004
8 1607 57977422 2004
>
I need to do a filter per year, such that for each year I consider a subset of rows for which year_prior