RPYS (Reference Publication Year Spectroscopy) Frame

>>> from techminer2.packages.rpys import RPYSDataFrame
>>> (
...     RPYSDataFrame()
...     #
...     # DATABASE:
...     .where_root_directory_is("example/")
...     .run()
... ).head()
      Num References  Median
2015               1    -1.0
2016               7    -7.0
2017              10   -10.0
2018              17   -17.0
2019              15    -5.0