boy names that became girl names (and vice versaanother fun trend is looking at boy names that were more popular with one sex earlier in the sample but have "changed sexesin the present one example is the name lesley or leslie going back to the top dataseti compute list of names occurring in the dataset starting with 'lesl'in [ ]all_names top name unique(in [ ]mask np array(['leslin lower(for in all_names]in [ ]lesley_like all_names[maskin [ ]lesley_like out[ ]array([leslielesleylesleeleslilesly]dtype=objectfrom therewe can filter down to just those names and sum births grouped by name to see the relative frequenciesin [ ]filtered top [top name isin(lesley_like)in [ ]filtered groupby('name'births sum(out[ ]name leslee lesley lesli leslie lesly namebirths nextlet' aggregate by sex and year and normalize within year introductory examples www it-ebooks info