如何将运动员的名字最有效地分配到新列“Firstname”中?

假设有一个数据帧:

country       Edition     sports       Athletes           Medal  Firstname
Germany          1990    Aquatics  HAJOS, Alfred          gold     Alfred
Germany          1990    Aquatics  HIRSCHMANN, Otto       silver   Otto
Germany          1990    Aquatics  DRIVAS, Dimitrios      silver   Dimitrios
US               2008    Athletics MALOKINIS, Ioannis     gold     Ioannis
US               2008    Athletics HAJOS, Alfred          silver   Alfred
US               2009    Athletics CHASAPIS, Spiridon     gold     Spiridon
France           2010    Athletics CHOROPHAS, Efstathios  gold     Efstathios
France           2010    Athletics CHOROPHAS, Efstathios  gold     Efstathios
France           2010    golf      HAJOS, Alfred          Bronze   Alfred 
France           2011    golf      ANDREOU, Joannis       silver   Joannis 
Spain            2011    golf      BURKE, Thomas          gold     Thomas

谁能告诉我如何分配运动员的名字到新的列'Firstname'最有效的方式?添加新列df['Firstname']后? 问题来源StackOverflow 地址：/questions/59379742/how-to-assign-firstname-of-athletes-to-new-column-firstname-in-most-efficient