在 DataFrame 列內減去

Question

會因為也許我今晚沒睡但是，鑒於：

df1 = {'Name':['Tom', 'Jack', 'Steve', 'Ricky'], index=['rank1','rank2','rank3','rank4']}
df2 = {'Age':[28,34,29,42],'bubu':[98,33,3,30], index=['rank1','rank2','rank3','rank4']}
df_merged = = pd.concat([ df1, df2 ], axis = 1)

現在，為了動態管理來自更列密集 df 的列的進一步算術運算：

a = ['Age']  #List
b = ['bubu'] #List

算術運算：

df_merged['newCol'] = df_merged[a]-df_merged[b]

或兩者

df_merged.assign(newCol = df_merged[a] - df_merged[b])

我不能減去 2 列因為返回這樣的錯誤

ValueError: Expected a 1D array, got an array with shape (556, 2)

Answer 1

不確定我是否理解，但試試這個：

a = 'Age'
b = 'bubu'

然后

df_merged['newCol'] = df_merged[a] - df_merged[b]

產生：

        Name  Age  bubu  newCol
rank1    Tom   28    98     -70
rank2   Jack   34    33       1
rank3  Steve   29     3      26
rank4  Ricky   42    30      12

那是你想要的嗎？

Answer 2

df_merged['newCol'] = df_merged['Age']-df_merged['bubu'] or
df_merged.insert(3,'newCol', df_merged['Age']-df_merged['bubu'],True)