trying to understand the python code

[buran]

1.actualScore will be just the column Score from the dataframe
2.actualScore.map(partition) will apply (i.e. map) function partition to every element of the actualScore, creating positiveNegative
3.filtered_data['Score'] = positiveNegative will replace values from column Score in the dataframe with values from positiveNegative
as a result the dataframe Score column will have just values positive (i.e. original score>=3) and negativee (i.e. original Score<3)