设置与复制警告:正在尝试在数据帧中的切片副本上设置值

Question

for i in range(0,len(donor_df)):
if donor_df['cand_nm'][i] == 'Obama, Barack':
donor_df['Party'] = 'Democrat'
else:
donor_df['Party'] = 'Republican'

donor_df是一个数据帧，想要创建一个名为"party"的新列，但它没有给出输出

Answer 1

您正在寻找np.where

donor_df['Party']=np.where(donor_df['cand_nm'] == 'Obama, Barack','Democrat','Republican')